Imunon (IMNN) 10-Q 15 Nov 21 2021 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2021	Nov. 12, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity File Number	001-15911
Entity Registrant Name	CELSION CORPORATION
Entity Central Index Key	0000749647
Entity Tax Identification Number	52-1256615
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	997 Lenox Drive
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Lawrenceville
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08648
City Area Code	(609)
Local Phone Number	896-9100
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	CLSN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		86,557,736

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 25,648,849	$ 17,164,177
Investment in debt securities - available for sale, at fair value	28,864,364
Accrued interest on investment in debt securities	38,404
Advances and deposits on clinical programs and other current assets	2,213,262	1,660,695
Total current assets	56,764,879	18,824,872
Property and equipment (at cost, less accumulated depreciation and amortization)	486,022	294,551
Other assets:
Money market investments, restricted cash	6,000,000
Deferred income tax asset		1,845,823
In-process research and development, net	13,366,234	13,366,234
Goodwill	1,976,101	1,976,101
Operating lease right-of-use assets, net	816,520	1,047,336
Other intangible assets, net		113,660
Deposits and other assets	58,761	58,761
Total other assets	22,217,616	18,407,915
Total assets	79,468,517	37,527,338
Current liabilities:
Accounts payable – trade	2,615,992	2,244,847
Other accrued liabilities	2,824,788	2,458,532
Notes payable – current portion, net of deferred financing costs		1,116,663
Operating lease liability - current portion	534,256	433,413
Deferred revenue - current portion	500,000	500,000
Total current liabilities	6,475,036	6,753,455
Earn-out milestone liability	7,345,000	7,018,000
Notes payable – non-current portion, net of deferred financing costs	5,808,774	3,934,497
Operating lease liability - non-current portion	373,526	710,305
Deferred revenue - non-current portion	125,000	500,000
Total liabilities	20,127,336	18,916,257
Commitments and contingencies
Stockholders’ equity:
Preferred Stock - $0.01 par value (100,000 shares authorized, and no shares issued or outstanding at September 30, 2021 and December 31, 2020)
Common stock - $0.01 par value (112,500,000 shares authorized; 86,558,070 and 40,701,356 shares issued at September 30, 2021 and December 31, 2020, respectively, and 86,557,736 and 40,701,022 shares outstanding at September 30, 2021 and December 31, 2020, respectively)	865,581	407,014
Additional paid-in capital	387,106,934	330,289,596
Accumulated other comprehensive loss	2,139
Accumulated deficit	(328,548,285)	(312,000,341)
Total stockholders’ equity before treasury stock	59,426,369	18,696,269
Treasury stock, at cost (334 shares at September 30, 2021 and December 31, 2020)	(85,188)	(85,188)
Total stockholders’ equity	59,341,181	18,611,081
Total liabilities and stockholders’ equity	$ 79,468,517	$ 37,527,338

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	112,500,000	112,500,000
Common stock, shares issued	86,558,070	40,701,356
Common stock, shares outstanding	86,557,736	40,701,022
Treasury stock, shares	334	334

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Licensing revenue	$ 125,000	$ 125,000	$ 375,000	$ 375,000
Operating expenses:
Research and development	2,468,066	2,491,696	7,633,051	8,534,606
General and administrative	2,718,510	1,792,904	8,258,271	5,532,946
Total operating expenses	5,186,576	4,284,600	15,891,322	14,067,552
Loss from operations	(5,061,576)	(4,159,600)	(15,516,322)	(13,692,552)
Other (expense) income:
Loss from change in fair-value of earn-out milestone liability	(257,000)	(1,099,721)	(327,000)	(1,397,291)
Impairment of in-process research and development		(2,370,257)		(2,370,257)
Investment income	3,552	10,114	5,614	119,383
Interest expense	(95,520)	(450,732)	(474,361)	(1,130,699)
Recognized loss on extinguishment of debt			(234,419)
Other (expense) income		(1,400)	(1,456)	7
Total other (expense) income, net	(348,968)	(3,911,996)	(1,031,622)	(4,778,857)
Net loss	$ (5,410,544)	$ (8,071,596)	$ (16,547,944)	$ (18,471,409)
Net loss per common share
Basic and diluted	$ (0.06)	$ (0.24)	$ (0.21)	$ (0.62)
Weighted average shares outstanding
Basic and diluted	86,557,736	34,112,254	79,667,613	29,934,764

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive loss (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Changes in:
Realized (gains) losses on debt securities recognized in investment income, net	$ 2,736	$ (7,257)	$ 4,521	$ (53,354)
Unrealized (losses) gains on debt securities, net	3,173	(609)	(2,382)	10,576
Change in unrealized (losses) gains on available for sale securities, net	5,909	(7,866)	2,139	(42,778)
Net loss	(5,410,544)	(8,071,596)	(16,547,944)	(18,471,409)
Comprehensive loss	$ (5,404,635)	$ (8,079,462)	$ (16,545,805)	$ (18,514,187)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (5,410,544)	$ (8,071,596)	$ (16,547,944)	$ (18,471,409)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization			542,740	572,065
Change in fair value of earn-out milestone liability	257,000	1,099,721	327,000	1,397,291
Recognition of deferred revenue			(375,000)	(375,000)
Stock-based compensation costs			3,073,569	1,448,202
Deferred income tax asset			1,845,823	1,819,324
Impairment of in-process research and development		2,370,257		2,370,257
Amortization of deferred finance charges and debt discount associated with notes payable			191,571	439,786
Fair value of warrants issued in exchange for services				44,798
Net changes in:
Accrued interest on investment securities			(38,404)	21,369
Advances, deposits, and other current assets			(552,567)	(286,991)
Accounts payable and accrued liabilities			397,701	(866,748)
Net cash used in operating activities			(11,135,511)	(11,887,056)
Cash flows from investing activities:
Purchases of investment securities			(40,862,225)	(9,956,892)
Proceeds from sale and maturity of investment securities			12,000,000	17,900,000
Purchases of property and equipment			(285,971)	(13,918)
Net cash (used in) provided by investing activities			(29,148,196)	7,929,190
Cash flows from financing activities:
Proceeds from sale of common stock equity, net of issuance costs			52,688,945	20,250,426
Proceeds from issuance of common stock upon conversion of stock warrants			1,508,666
Proceeds from issuance of common stock upon conversion of stock options			4,725	371,895
Proceeds from the SVB Loan Facility, net of issuance costs			5,756,630
Payoff of the Horizon Credit Agreement and accrued end of term fees			(5,190,587)	(5,200,000)
Proceeds from Payroll Protection Program (PPP) loans				1,324,750
Repayments on Payroll Protection Program (PPP) loans				(1,324,750)
Net cash provided by financing activities			54,768,379	15,422,321
Change in cash, cash equivalents and restricted cash			14,484,672	11,464,455
Cash, cash equivalents and restricted cash at beginning of period			17,164,177	6,875,273	$ 6,875,273
Cash, cash equivalents and restricted cash at end of period	$ 31,648,849	$ 18,339,728	31,648,849	18,339,728	$ 17,164,177
Supplemental disclosures of cash flow information:
Interest paid			(307,985)	(685,913)
Cash paid for amounts included in measurement of lease liabilities:
Operating cash flows from lease payments			418,696	393,947
Common stock issued to settle accrued bonuses				498,632
Fair value of warrants issued in connection with debt facility, net of cancelled warrants				81,102
Realized and unrealized gains (losses), net, on investment securities			$ 2,139	$ (42,778)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Beginning balance, value at Dec. 31, 2019	$ 232,562	$ 304,885,663	$ (85,188)	$ 42,778	$ (290,516,780)	$ 14,559,035
Beginning balance, shares at Dec. 31, 2019	23,255,818		334
Net loss					(18,471,409)	(18,471,409)
Sale of equity through equity financing facilities	$ 123,301	20,127,125				20,250,426
Sale of equity through equity financing facilities, shares	12,330,243
Issuance of common stock upon exercise of options	$ 1,409	370,486				371,895
Issuance of common stock upon exercise of options, shares	140,864
Common stock warrants issued in exchange for services		44,798				44,798
Issuance of restricted stock	$ 30	(30)
Issuance of restricted stock, shares	3,000
Realized and unrealized gains and losses, net, on investments securities				(42,778)		(42,778)
Stock-based compensation expense		1,448,202				1,448,202
Common stock issued to settle accrued bonuses	$ 4,299	494,333				498,632
Common stock issued to settle accrued bonuses	429,855
Ending balance, value at Sep. 30, 2020	$ 361,601	327,370,577	$ (85,188)		(308,988,189)	18,658,801
Ending balance, shares at Sep. 30, 2020	36,159,780		334
Beginning balance, value at Dec. 31, 2019	$ 232,562	304,885,663	$ (85,188)	42,778	(290,516,780)	14,559,035
Beginning balance, shares at Dec. 31, 2019	23,255,818		334
Ending balance, value at Dec. 31, 2020	$ 407,014	330,289,596	$ (85,188)		(312,000,341)	18,611,081
Ending balance, shares at Dec. 31, 2020	40,701,022		334
Beginning balance, value at Jun. 30, 2020	$ 332,297	324,869,780	$ (85,188)	7,866	(300,916,593)	24,208,162
Beginning balance, shares at Jun. 30, 2020	33,229,380		334
Net loss					(8,071,596)	(8,071,596)
Sale of equity through equity financing facilities	$ 29,274	2,038,553				2,067,827
Sale of equity through equity financing facilities, shares	2,927,400
Common stock warrants issued in exchange for services		44,798				44,798
Issuance of restricted stock	$ 30	(30)
Issuance of restricted stock, shares	3,000
Realized and unrealized gains and losses, net, on investments securities				(7,866)		(7,866)
Stock-based compensation expense		417,476				417,476
Ending balance, value at Sep. 30, 2020	$ 361,601	327,370,577	$ (85,188)		(308,988,189)	18,658,801
Ending balance, shares at Sep. 30, 2020	36,159,780		334
Beginning balance, value at Dec. 31, 2020	$ 407,014	330,289,596	$ (85,188)		(312,000,341)	18,611,081
Beginning balance, shares at Dec. 31, 2020	40,701,022		334
Net loss					(16,547,944)	(16,547,944)
Sale of equity through equity financing facilities	$ 446,326	52,242,619				52,688,945
Sale of equity through equity financing facilities, shares	44,632,547
Shares issued upon exercise of common stock warrants, net of fees	$ 12,166	1,496,500				1,508,666
Shares issued upon exercise of common stock warrants, net of fees	1,216,667
Shares issued upon exercise of options to purchase common stock	$ 75	4,650				4,725
Shares issued upon exercise of options to purchase common stock, shares	7,500
Realized and unrealized gains and losses, net, on investments securities				2,139		2,139
Stock-based compensation expense		3,073,569				3,073,569
Ending balance, value at Sep. 30, 2021	$ 865,581	387,106,934	$ (85,188)	2,139	(328,548,285)	59,341,181
Ending balance, shares at Sep. 30, 2021	86,557,736		334
Beginning balance, value at Jun. 30, 2021	$ 865,581	386,414,630	$ (85,188)	(3,770)	(323,137,741)	64,053,512
Beginning balance, shares at Jun. 30, 2021	86,557,736		334
Net loss					(5,410,544)	(5,410,544)
Sale of equity through equity financing facilities		(8,320)				(8,320)
Sale of equity through equity financing facilities, shares
Realized and unrealized gains and losses, net, on investments securities				5,909		5,909
Stock-based compensation expense		700,624				700,624
Ending balance, value at Sep. 30, 2021	$ 865,581	$ 387,106,934	$ (85,188)	$ 2,139	$ (328,548,285)	$ 59,341,181
Ending balance, shares at Sep. 30, 2021	86,557,736		334

Business Description

Business Description	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Business Description	Note 1. Business Description Celsion Corporation (“Celsion” and the “Company”) is a fully integrated, clinical stage biotechnology company focused on advancing a portfolio of innovative treatments including DNA-based immunotherapies, next generation vaccines and directed chemotherapies through clinical trials and eventual commercialization. The Company’s product pipeline includes GEN-1, a DNA-based immunotherapy for the localized treatment of ovarian cancer and ThermoDox ®

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Note 2. Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which include the accounts of the Company and its wholly owned subsidiaries, CLSN Laboratories, Inc. and Celsion, GmbH, have been prepared in accordance with generally accepted accounting principles in the United States (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. All significant intercompany balances and transactions have been eliminated in consolidation. Certain information and disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments, consisting only of normal recurring accruals considered necessary for a fair presentation, have been included in the accompanying unaudited condensed consolidated financial statements. Operating results for the three-month and nine-month periods ended September 30, 2021 and 2020 are not necessarily indicative of the results that may be expected for any other interim period(s) or for any full year. For further information, refer to the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 filed with the Securities and Exchange Commission (SEC) on March 19, 2021. The preparation of financial statements in conformity with GAAP requires management to make judgments, estimates, and assumptions that affect the amount reported in the Company’s financial statements and accompanying notes. Actual results could differ materially from those estimates. Events and conditions arising subsequent to the most recent balance sheet date have been evaluated for their possible impact on the financial statements and accompanying notes. The Company continues to monitor the impact of the COVID-19 pandemic on its financial condition and results of operations, along with the valuation of its long-term assets, intangible assets, and goodwill. The effect of this matter could potentially have an impact on the valuation of such assets in the future. The COVID-19 pandemic is discussed in more detail in Note 3 to the financial statements.

Financial Condition and Busines

Financial Condition and Business Plan	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Financial Condition and Business Plan	Note 3. Financial Condition and Business Plan Since inception, the Company has incurred substantial operating losses, principally from expenses associated with the Company’s research and development programs, clinical trials conducted in connection with the Company’s product candidates, and applications and submissions to the U.S. Food and Drug Administration. The Company has not generated significant revenue and has incurred significant net losses in each year since our inception. As of September 30, 2021, the Company has incurred approximately $ 329 60.6 The Company expects its operating losses to continue for the foreseeable future as it continues its product development efforts, and when it undertakes marketing and sales activities. The Company’s ability to achieve profitability is dependent upon its ability to obtain governmental approvals, manufacture, and market and sell its product candidates. There can be no assurance that the Company will be able to commercialize its technology successfully or that profitability will ever be achieved. The operating results of the Company have fluctuated significantly in the past. In January 2020, the WHO declared an outbreak of coronavirus, COVID-19, to be a “Public Health Emergency of International Concern,” and the U.S. Department of Health and Human Services declared a public health emergency to aid the U.S. healthcare community in responding to COVID-19. This virus has spread to over 100 countries, including the U.S. Governments and businesses around the world have taken unprecedented actions to mitigate the spread of COVID-19, including, but not limited to, shelter-in-place orders, quarantines, significant restrictions on travel, as well as restrictions that prohibit many employees from going to work. Uncertainty with respect to the economic impacts of the pandemic has introduced significant volatility in the financial markets. The Company did not observe significant impacts on its business or results of operations during 2020 and into 2021 due to COVID-19. While the extent to which COVID-19 impacts the Company’s future results will depend on future developments, the pandemic and associated economic impacts could result in a material impact to the Company’s future financial condition, results of operations and cash flows. The Company’s ability to raise additional capital may be adversely impacted by potential worsening global economic conditions and the recent disruptions to, and volatility in, financial markets in the U.S. and worldwide resulting from the ongoing COVID-19 pandemic. The disruptions caused by COVID-19 may also disrupt the clinical trials process and enrolment of patients. This may delay commercialization efforts. The Company continues to monitor its operating activities in light of these events. The specific impact, if any, is not readily determinable as of the date of these financial statements. The actual amount of funds the Company will need to operate is subject to many factors, some of which are beyond the Company’s control. These factors include the following: ● the progress of research activities; ● the number and scope of research programs; ● the progress of preclinical and clinical development activities; ● the progress of the development efforts of parties with whom the Company has entered into research and development agreements; ● the costs associated with additional clinical trials of product candidates; ● the ability to maintain current research and development licensing arrangements and to establish new research and development and licensing arrangements; ● the ability to achieve milestones under licensing arrangements; ● the costs involved in prosecuting and enforcing patent claims and other intellectual property rights; and ● the costs and timing of regulatory approvals. On July 13, 2020, the Company announced that it has received a recommendation from the independent Data Management Committee (“DMC”) to consider stopping the global Phase III OPTIMA Study of ThermoDox ® During 2020, 2019 and 2018, the Company submitted applications to sell a portion of the Company’s State of New Jersey net operating losses as part of the Technology Business Tax Certificate Program sponsored by The New Jersey Economic Development Authority. Under the program, emerging biotechnology companies with unused NOLs and unused research and development credits are allowed to sell these benefits to other New Jersey-based companies. In 2018 and 2019, the Company sold cumulative NOL’s from 2011 to 2018 NOLs totaling $ 13 12.2 2.0 1.85 15 20 1.6 1.4 In June 2018, the Company entered into a Credit Agreement with Horizon Technology Finance Corporation (“Horizon”) that provided $ 10 Payments under the loan agreement are interest only (calculated based on one-month LIBOR plus 7.625 5 10 0.2 5 10 6 4 3.25 As more fully discussed in Note 12, during 2021 through the date of the filing of this Quarterly Report on Form 10-Q, the Company has raised approximately $ 6.9 TM 35 15 1.5 60.6 The Company has based its estimates on assumptions that may prove to be wrong. The Company may need to obtain additional funds sooner or in greater amounts than it currently anticipates. Potential sources of financing include strategic relationships, public or private sales of the Company’s shares or debt, the sale of the Company’s State of New Jersey net operating losses and other sources. If the Company raises funds by selling additional shares of common stock or other securities convertible into common stock, the ownership interest of existing stockholders may be diluted.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2021
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	Note 4. New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) and are adopted by us as of the specified effective date. Unless otherwise discussed, we believe that the impact of recently issued accounting pronouncements will not have a material impact on the Company’s condensed consolidated financial position, results of operations, and cash flows, or do not apply to our operations. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740) In connection with the upcoming elimination of the London Inter-bank Offered Rate, (“LIBOR”) and other reference interest rates, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Reform on Financial Reporting In May 2021, the FASB issued ASU No. 2021-04 “ Earnings Per Share (Topic 260), Debt-Modifications and Extinguishments (Subtopic 470-50), Compensation-Stock Compensation (Topic 718), and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options (a consensus of the FASB Emerging Issues Task Force)”.

Restricted Cash

Restricted Cash	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Restricted Cash	Note 5. Restricted Cash As a condition of the $ 10 million loan facility with Silicon Valley Bank (“SVB”) entered into on June 18, 2021 as further discussed in Note 11, the Company is required at all times to maintain on deposit with SVB as cash collateral in a segregated money market bank account in the name of the Company, unrestricted and unencumbered cash (other than a lien in favor of SVB) in an amount of at least 100% of the aggregate outstanding amount of the SVB loan facility. SVB may restrict withdrawals or transfers by or on behalf of the Company that would violate this requirement. The required reserve totaled $ 6.0 million as of September 30, 2021. This amount is presented in part as restricted cash in other non-current assets on the accompanying condensed consolidated balance sheets. The following table reconciles cash and cash equivalents and restricted cash per the balance sheet to the condensed statements of cash flows: Schedule of Cash and Cash Equivalents and Restricted Cash September 30, 2021 September 30, 2020 Cash and cash equivalents $ 25,648,849 $ 18,339,728 Money market investments, restricted 6,000,000 - Total $ 31,648,849 $ 18,339,728

Net Loss per Common Share

Net Loss per Common Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Common Share	Note 6. Net Loss per Common Share Basic loss per share is calculated based upon the net loss available to common shareholders divided by the weighted average number of common shares outstanding during the period. Diluted loss per share is calculated after adjusting the denominator of the basic earnings per share computation for the effects of all dilutive potential common shares outstanding during the period. The dilutive effects of preferred stock, options and warrants and their equivalents are computed using the treasury stock method. The total number of shares of common stock issuable upon exercise of warrants, stock option grants and equity awards were 9,250,354 8,507,041 0.01 200,000

Investment in Debt Securities-A

Investment in Debt Securities-Available for Sale	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Investment in Debt Securities-Available for Sale	Note 7. Investment in Debt Securities-Available for Sale Investments in debt securities available for sale with a fair value of $ 28,864,364 Investments in debt securities available for sale are evaluated periodically to determine whether a decline in their value is other than temporary. The term “other than temporary” is not intended to indicate a permanent decline in value. Rather, it means that the prospects for near term recovery of value are not necessarily favorable, or that there is a lack of evidence to support fair values equal to, or greater than, the carrying value of the security. Management reviews criteria such as the magnitude and duration of the decline, as well as the reasons for the decline, to predict whether the loss in value is other than temporary. Once a decline in value is determined to be other than temporary, the value of the security is reduced and a corresponding charge to earnings is recognized. A summary of the cost, fair value and maturities of the Company’s short-term investments is as follows: Schedule of Cost, Fair Value and Maturities of Short Term Investments September 30, 2021 December 31, 2020 Cost Fair Value Cost Fair Value Short-term investments Commercial paper $ 7,784,165 $ 7,784,894 $ - - Government backed debt securities 21,078,059 21,079,470 - - Total $ 28,862,224 $ 28,864,364 $ - $ - September 30, 2021 December 31, 2020 Cost Fair Value Cost Fair Value Short-term investment maturities Within 3 months $ 11,998,304 $ 11,999,400 $ - $ - Between 3-12 months 16,863,920 16,864,964 - - Total $ 28,862,224 $ 28,864,364 $ - $ - The following table shows the Company’s investment in debt securities available for sale gross unrealized gains (losses) and fair value by investment category and length of time that individual securities have been in a continuous unrealized loss position at September 30, 2021 and December 31, 2020. The Company has reviewed individual securities to determine whether a decline in fair value below the amortizable cost basis is other than temporary. Summary of Investment Securities Gross Unrealized Gains (Losses) September 30, 2021 December 31, 2020 Available for sale securities (all unrealized holding gains and losses are less than 12 months at date of measurement) Fair Value Unrealized Holding Gains (Losses) Fair Value Unrealized Holding Gains (Losses) Investments with unrealized gains $ 21,029,520 $ 3,055 $ - $ - Investments with unrealized losses 7,834,844 (916 ) - - Total $ 28,864,364 $ 2,139 $ - $ - Investment (loss) income, which includes net realized losses on sales of available for sale securities and investment income interest and dividends, is summarized as follows: Summary of Net Realized Losses on Sales of Available for Sale Securities and Investment Income Interest and Dividends 2021 2020 Three Months Ended September 30, 2021 2020 Interest and dividends accrued and paid $ 6,288 $ 2,857 Realized (losses) gains (2,736 ) 7,257 Investment income, net $ 3,552 $ 10,114 2021 2020 Nine Months Ended September 30, 2021 2020 Interest and dividends accrued and paid $ 10,135 $ 66,029 Realized (losses) gains (4,521 ) 53,354 Investment income, net $ 5,614 $ 119,383

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Measurements
Fair Value Measurements	Note 8. Fair Value Measurements FASB ASC Section 820, Fair Value Measurements and Disclosures Level 1: Quoted prices (unadjusted) or identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date; Level 2: Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data; and Level 3: Significant unobservable inputs that reflect a reporting entity’s own assumptions that market participants would use in pricing an asset or liability. Cash and cash equivalents, other current assets, accounts payable and other accrued liabilities are reflected in the condensed consolidated balance sheet at their approximate estimated fair values primarily due to their short-term nature. The fair values of securities available for sale is determined by relying on the securities’ relationship to other benchmark quoted securities and classified its investments as Level 2 items in both 2021 and 2020. There were no transfers of assets or liabilities between Level 1 and Level 2 and no transfers in or out of Level 3 during the nine-months ended September 30, 2021 or during the year ended December 31, 2020. The changes in Level 3 liabilities were the result of changes in the fair value of the earn-out milestone liability included in earnings and in-process R&D. The earnout milestone liability is valued using a risk-adjusted assessment of the probability of payment of each milestone, discounted to present value using an estimated time to achieve the milestone (see Note 14). Assets and liabilities measured at fair value are summarized below: Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Total Fair Value Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Recurring items as of September 30, 2021 Investment in debt securities - available for sale, at fair value $ 28,864,364 $ – $ 28,864,364 $ – Non-recurring items as of September 30, 2021 In-process R&D (Note 9) $ 13,366,234 $ – $ – $ 13,366,234 Non-recurring items as of December 31, 2020 In-process R&D (Note 9) $ 13,366,234 $ – $ – $ 13,366,234 Liabilities: Recurring items as of September 30, 2021 Earn-out milestone liability (Note 14) $ 7,345,000 $ – $ – $ 7,345,000 Recurring items as of December 31, 2020 Earn-out milestone liability (Note 14) $ 7,018,000 $ – $ – $ 7,018,000

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Note 9. Intangible Assets In June 2014, we completed the acquisition of substantially all of the assets of EGEN, Inc., an Alabama corporation, which has changed its company name to EGWU, Inc. after the closing of the acquisition (“EGEN”). We acquired all of EGEN’s right, title and interest in and to substantially all of the assets of EGEN, including cash and cash equivalents, patents, trademarks and other intellectual property rights, clinical data, certain contracts, licenses and permits, equipment, furniture, office equipment, furnishings, supplies and other tangible personal property. In addition, CLSN Laboratories assumed certain specified liabilities of EGEN, including the liabilities arising out of the acquired contracts and other assets relating to periods after the closing date. Acquired In-process Research and Development Acquired in-process research and development (IPR&D) consists of EGEN’s drug technology platforms: TheraPlas and TheraSilence. The fair value of the IPR&D drug technology platforms was estimated to be $ 24.2 The Company’s ovarian cancer indication, with original value of $ 13.3 no The Company’s GBM candidate, with original value of $ 9.4 7 2.4 2.4 2.4 Covenants Not to Compete Pursuant to the EGEN Purchase Agreement, EGEN provided certain covenants (“Covenant Not To Compete”) to the Company whereby EGEN agreed, during the period ending on the seventh anniversary of the closing date of the acquisition on June 20, 2014, not to enter into any business, directly or indirectly, which competes with the business of the Company, nor will it contact, solicit or approach any of the employees of the Company for purposes of offering employment. The Covenant Not to Compete which was valued at approximately $ 1.6 7 years 113,660 113,660 1,477,554 56,830 170,487 Goodwill The purchase price exceeded the estimated fair value of the net assets acquired by approximately $ 2.0 Following is a summary of the net fair value of the assets acquired in the EGEN asset acquisition for the nine-month period ended September 30, 2021: Schedule of Fair Value of Assets Acquired IPR&D Goodwill Covenant Not To Compete For the nine-months ended September 30, 2021 Balance at January 1, 2021, net $ 13,366,234 $ 1,976,101 $ 113,660 Amortization - - (113,660 ) Balance at September 30, 2021, net $ 13,366,234 $ 1,976,101 $ -

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Accrued Liabilities	Note 10. Accrued Liabilities Other accrued liabilities at September 30, 2021 and December 31, 2020 include the following: Schedule of Accrued Liabilities September 30, 2021 December 31, 2020 Amounts due to contract research organizations and other contractual agreements $ 1,276,317 $ 636,000 Accrued payroll and related benefits 1,247,460 1,736,271 Accrued professional fees 265,350 66,850 Accrued interest 16,250 - Other 19,411 19,411 Total $ 2,824,788 $ 2,458,532

Notes Payable

Notes Payable	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Notes Payable	Note 11. Notes Payable The SVB Loan Facility On June 18, 2021, the Company entered into a $ 10 6 6.0 4 The SVB Loan Facility is in the form of money market secured indebtedness bearing interest at a calculated WSJ Prime-based variable rate (currently 3.25 3 10 Payments under the loan agreement are interest only for the first 24 months after loan closing, followed by a 24-month amortization period of principal and interest through the scheduled maturity date. In connection with the SVB Loan Facility, the Company incurred financing fees and expenses totaling $ 243,370 3.0 300,000 49,883 56,875 45,687 52,144 Following is a schedule of future principal payments, net of unamortized debt discounts and amortized end-of-term fee, due on the SVB Loan Facility: Schedule of Future Principle Payments, Net of Unamortized Debt Discounts As of September 30, 2022 $ – 2023 750,000 2024 3,000,000 2025 and thereafter 2,250,000 Subtotal of future principal payments 6,000,000 Unamortized debt premium, net (191,226 ) Total $ 5,808,774 Horizon Credit Agreement On June 27, 2018, the Company entered into a loan agreement with Horizon Technology Finance Corporation (“Horizon”) that provided $ 10 10 5 0.2 5 Pursuant to the Amendment, the remaining $ 5 The obligations bore interest at a rate calculated based an amount by which the one-month LIBOR exceeds 2% plus 7.625%. In no event shall the interest rate be less than 9.625%. Payments pursuant to the Amendment were interest only for the first twelve (12) months after August 1, 2020, followed by a 21-month amortization period of principal and interest through the scheduled maturity date on April 1, 2023. In addition, the remaining $ 5 275,000 In connection with the Amendment, Celsion agreed to a liquidity covenant which provides that, at all times, Celsion shall maintain unrestricted cash and/or cash equivalents on deposit in accounts over which the applicable Lenders maintain an account control agreement in an amount not less than $2.5 million. In addition, pursuant to the Amendment, Celsion agreed to provide evidence to Horizon on or before March 31, 2021, that it received aggregate cash proceeds of not less than $5 million from the sale of equity, debt, its New Jersey net operating losses, or a combination thereof, subsequent to the date of the Amendment. The Company met this requirement during the fourth quarter of 2020. In connection with the Horizon Credit Agreement, the Company incurred financing fees and expenses totaling $ 175,000 100,000 782,116 4.0 400,000 As a fee in connection with the Horizon Credit Agreement, Celsion issued Horizon warrants exercisable for a total of 190,114 2.63 507,116 95,057 1.01 247,525 95,057 The New Warrants were immediately exercisable for cash or by net exercise from the date of grant and will expire after ten years from the date of grant. The Horizon Credit Agreement contains customary representations, warranties and affirmative and negative covenants including, among other things, covenants that limit or restrict Celsion’s ability to grant liens, incur indebtedness, make certain restricted payments, merge, or consolidate and make dispositions of assets. The Amendment was evaluated in accordance with FASB ASC 470-50, Debt-Modifications and Extinguishments 5 0.2 We accounted for the remaining $ 5 5,000 247,548 109,706 275,000 142,605 No 225,920 139,428 198,738 251,993 685,913 444,786 On June 18, 2021, as a condition of entering into the SVB Loan Facility, the Company paid the outstanding principal balance, an early termination fee and the end of term charges in full satisfaction of the Horizon Credit Agreement, as amended. Following is a schedule of the amounts paid to Horizon on June 18, 2021. Schedule of Debt Principal balance at June 18, 2021 $ 5,000,000 Early termination fees 150,000 End of term charges 275,000 Total $ 5,425,000 During the nine months ended September 30, 2021, the Company recorded a loss of $ 234,419 190,581

Stockholders_ Equity

Stockholders’ Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Stockholders’ Equity	Note 12. Stockholders’ Equity In September 2018, the Company filed with the SEC a $ 75 On March 19, 2021, the Company filed with the SEC a new $ 100 Capital on Demand TM On December 4, 2018, the Company entered into the Capital on Demand Agreement with JonesTrading, pursuant to which the Company may offer and sell, from time to time, through JonesTrading shares of Common Stock having an aggregate offering price of up to $ 16.0 During 2020 through September 30, 2020, the Company sold and issued an aggregate of 2.1 4.3 7.2 6.9 Registered Direct Offering On February 27, 2020, we entered into a Securities Purchase Agreement (the “February 2020 Purchase Agreement”) with several institutional investors, pursuant to which we agreed to issue and sell, in a registered direct offering (the “February 2020 Offering”), an aggregate of 4,571,428 1.05 4.8 2,971,428 five 1.15 1.24 3,200,000 five 1.2 1.5 Underwritten Offering On June 22, 2020, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Oppenheimer & Co. Inc. (the “Underwriter”), relating to the issuance and sale (the “Underwritten Offering”) of 2,666,667 3.4875 3.75 0.2625 7.0 9.1 Pursuant to the Underwriting Agreement, until December 31, 2020, the Underwriter had a right of first refusal to act as sole underwriter, initial purchaser, placement/selling agent, or arranger, as the case may be, on any new financing for the Company (excluding equipment lease financings, loans or grants from governmental authorities or in connection with government programs and financings relating to or sales of tax attributes) during such period. The Underwriter had the sole right to determine whether or not any other broker dealer could participate in any such offering and the economic terms of any such participation. January 2021 Registered Direct Offering On January 22, 2021, the Company entered into a Securities Purchase Agreement (the “January 2021 Purchase Agreement”) with several institutional investors, pursuant to which the Company agreed to issue and sell, in a registered direct offering (the “January 2021 Offering”), an aggregate of 25,925,925 1.35 35 In connection with the January 2021 Offering, the Company entered into a placement agent agreement (the “January 2021 Placement Agent Agreement”) with A.G.P./Alliance Global Partners (together with Brookline Capital Markets, the “January 2021 Placement Agents”) pursuant to which the Company agreed to pay the January 2021 Placement Agents a cash fee equal to 7% of the aggregate gross proceeds raised from the sale of the securities sold in the January 2021 Offering and reimburse the January 2021 Placement Agents for certain of their expenses in an amount not to exceed $82,500. March 2021 Registered Direct Offering On March 31, 2021, the Company entered into a Securities Purchase Agreement (the “March 2021 Purchase Agreement”) with several institutional investors, pursuant to which the Company agreed to issue and sell, in a registered direct offering (the “March 2021 Offering”), an aggregate of 11,538,462 1.30 15 In connection with the March 2021 Offering, the Company entered into a placement agent agreement (the “March 2021 Placement Agent Agreement”) with A.G.P./Alliance Global Partners, as lead placement agent (“AGP,” and together with JonesTrading Institutional Services LLC and Brookline Capital Markets, a division of Arcadia Securities, LLC, serving as co-placement agents, the “March 2021 Placement Agents”), pursuant to which the Company agreed to pay the March 2021 Placement Agents an aggregate cash fee equal to 7% of the aggregate gross proceeds raised from the sale of the securities sold in the Offering and reimburse the Placement Agents for certain of their expenses in an amount not to exceed $82,500. Under the March 2021 Purchase Agreement and March 2021 Placement Agent Agreement, the Company and its subsidiaries were prohibited, for a period of 90 days after the closing, from entering into any agreement to issue or announcing any issuance or proposed issuance of common stock or any other securities that are at any time convertible into, or exercisable or exchangeable for, or otherwise entitle the holder thereof to receive common stock without the prior written consent of AGP or the investors participating in the offering. For purposes of this offering, AGP and the investors from the Company’s January 2021 Offering waived a similar 90-day restriction in the placement agent agreement and purchase agreement for that transaction. LPC Purchase Agreement On September 8, 2020, the Company entered into a purchase agreement (the “LPC Purchase Agreement”) and a Registration Rights Agreement (the “Registration Rights Agreement”) with Lincoln Park Capital Fund, LLC (“Lincoln Park”), pursuant to which, upon the terms and subject to the conditions and limitations set forth therein, the Company has the right to sell to Lincoln Park up to $ 26.0 3.3 437,828 2.2

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Note 13. Stock-Based Compensation The Company has long-term compensation plans that permit the granting of equity-based awards in the form of stock options, restricted stock, restricted stock units, stock appreciation rights, other stock awards, and performance awards. At the 2018 Annual Stockholders Meeting of the Company held on May 15, 2018, stockholders approved the Celsion Corporation 2018 Stock Incentive Plan (the “2018 Plan”). The 2018 Plan, as adopted, permits the granting of 2,700,000 1,200,000 3,900,000 2,500,000 6,400,000 7,700,000 14,100,000 The Company has issued stock awards to employees and directors in the form of stock options and restricted stock. Options are generally granted with strike prices equal to the fair market value of a share of Celsion common stock on the date of grant. Incentive stock options may be granted to purchase shares of common stock at a price not less than 100% of the fair market value of the underlying shares on the date of grant, provided that the exercise price of any incentive stock option granted to an eligible employee owning more than 10% of the outstanding stock of Celsion must be at least 110% of such fair market value on the date of grant. Only officers and key employees may receive incentive stock options. Option and restricted stock awards vest upon terms determined by the Compensation Committee of the Board of Directors and are subject to accelerated vesting in the event of a change of control or certain terminations of employment. The Company issues new shares to satisfy its obligations from the exercise of options or the grant of restricted stock awards. On September 28, 2018, and again on February 19, 2019, the Compensation Committee of the Board of Directors approved the grant of (i) inducement stock options (the “Inducement Option Grants”) to purchase a total of 164,004 140,004 19,000 13,000 2.77 2.18 three years As of September 30, 2021, there were a total of 14,198,424 6,473,451 7,724,973 140,004 A summary of stock option awards and restricted stock grants for the nine-months ended September 30, 2021 is presented below: Summary of Stock Option Awards and Restricted Stock Grants Stock Options Restricted Stock Awards Weighted Average Options Outstanding Weighted Average Exercise Price Non-vested Restricted Stock Outstanding Weighted Average Grant Date Fair Value Contractual Terms of Equity Awards (in years) Equity awards outstanding at January 1, 2021 4,624,725 $ 2.77 2,750 $ 0.89 Equity awards granted 2,171,250 $ 2.17 9,000 $ 1.29 Equity awards exercised or vested and issued (7,500 ) $ 0.63 - $ - Equity awards forfeited, cancelled or expired (185,770 ) $ 2.59 (1,000 ) $ 2.22 Equity awards outstanding at September 30, 2021 6,602,705 $ 2.58 10,750 $ 1.33 7.8 Aggregate intrinsic value of outstanding equity awards at September 30, 2021 $ 2,538 $ 12,383 Equity awards exercisable at September 30, 2021 4,291,685 $ 2.73 7.2 Aggregate intrinsic value of equity awards exercisable at September 30, 2021 $ - Total compensation cost related to stock options and restricted stock awards amounted to $ 700,624 417,476 241,288 164,035 459,336 253,441 Total compensation cost related to stock options and restricted stock awards amounted to $ 3,073,569 1,448,202 1,123,376 542,157 1,950,193 906,045 As of September 30, 2021, there was $ 2.4 1.0 1.97 3.07 The fair values of stock options granted were estimated at the date of grant using the Black-Scholes option pricing model. The Black-Scholes model was originally developed for use in estimating the fair value of traded options, which have different characteristics from Celsion’s stock options. The model is also sensitive to changes in assumptions, which can materially affect the fair value estimate. The Company used the following assumptions for determining the fair value of options granted under the Black-Scholes option pricing model: Schedule of Assumptions Used to Determine Fair Value of Options Granted Nine Months Ended 2021 2020 Risk-free interest rate 1.54 1.74 % 0.66 1.33 % Expected volatility 106.8 113.2 % 100.4 104.8 % Expected life (in years) 7.5 10.0 8.0 10.0 Expected dividend yield - % - % Expected volatilities utilized in the model are based on historical volatility of the Company’s stock price. The risk-free interest rate is derived from values assigned to U.S. Treasury bonds with terms that approximate the expected option lives in effect at the time of grant.

Earn-Out Milestone Liability

Earn-Out Milestone Liability	9 Months Ended
	Sep. 30, 2021
Earn-out Milestone Liability
Earn-Out Milestone Liability	Note 14. Earn-Out Milestone Liability On March 28, 2019, the Company and EGWU, Inc. entered into an amendment to its purchase agreement (“Amended Asset Purchase Agreement”), whereby payment of the earnout milestone liability related to the Ovarian Cancer Indication of $ 12.4 a) $ 7.0 b) $ 12.4 As of September 30, 2021, June 30, 2021, and December 31, 2020, the Company calculated the fair value of the earn-out milestone liability at $ 7.3 7.1 7.0 0.3 In assessing the earnout milestone liability at September 30, 2021 and June 30, 2021, the Company determined the fair value of each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 50% and 50% probability for the $7.0 million and the $12.4 million payments, respectively. As of September 30, 2020, June 30, 2020 and December 31, 2019, the Company calculated the fair value of the earn-out milestone liability at $ 7.1 6.0 5.7 1.1 1.4 In assessing the earnout milestone liability at September 30, 2020, the Company fair valued each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 50% and 50% probability for the $7.0 million and the $12.4 million payments, respectively, and at June 30, 2020, the Company determined the fair value of each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 80% and 20% probability for the $7.0 million and the $12.4 million payments, respectively. The following is a summary of the changes in the earn-out milestone liability for the nine-month period ended September 30, 2021: Schedule of Changes in Earn-out Milestone Liability Balance at January 1, 2021 $ (7,018,000 ) Non-cash loss from the change in fair value (327,000 ) Balance at September 30, 2021 $ (7,345,000 ) The following is a schedule of the Company’s risk-adjustment assessment of each milestone: Schedule of Risk Adjustment Assessment Date Risk-adjustment Assessment of Achieving Each Milestone Discount Rate Estimated Time to Achieve September 30, 2021 80 % 6.54 6.60 % 0.29 1.29 June 30, 2021 80 % 9 % 0.42 1.42 December 31, 2020 80 % 9 % 0.54 1.54 September 30, 2020 80 % 9 % 0.38 1.38 June 30, 2020 80 % 9 % 0.54 1.54 December 31, 2019 80 % 9 % 1.12 2.12

Warrants

Warrants	9 Months Ended
	Sep. 30, 2021
Warrants
Warrants	Note 15. Warrants Following is a summary of all warrant activity for the nine-months ended September 30, 2021: Summary of Warrant Activity Warrants Number of Issued Weighted Average Exercise Price Warrants outstanding at December 31, 2020 3,853,566 $ 1.35 Warrants exercised during the nine months ended September 30, 2021 (see Note 12) (1,216,667 ) $ 1.24 Warrants outstanding at September 30, 2021 2,636,899 $ 1.40 Aggregate intrinsic value of outstanding warrants at September 30, 2021 $ 159,857 Weighted average remaining contractual terms at September 30, 2021 4.1

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases
Leases	Note 16. Leases In 2011, the Company executed a lease (the “Lease”) with Brandywine Operating Partnership, L.P. (Brandywine), a Delaware limited partnership, for a 10,870 66 April 30, 2017 st 18,900 20,500 st st increase the size of the premises by 2,285 square feet to 9,850 square feet and also extended the lease term by one year to September 1, 2023 25,035 27,088 nd In connection with the EGEN Asset Purchase Agreement in June 2014, the Company assumed the existing lease with another landlord for an 11,500 18,100 2,197 5,500 We adopted ASC Topic 842 on January 1, 2019 using the modified retrospective transition method for all lease arrangements at the beginning of the period of adoption. Results for reporting periods beginning January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be reported in accordance with our historic accounting under Topic 840, Leases. The standard had a material impact on our Condensed Consolidated Balance Sheet but had no impact on our condensed consolidated net earnings and cash flows. The most significant impact of adopting ASC Topic 842 was the recognition of the right-of-use (ROU) asset and lease liabilities for operating leases, which are presented in the following three-line items on the Consolidated Condensed Balance Sheet: (i) operating lease right-of-use asset; (ii) current operating lease liabilities; and (iii) operating lease liabilities. Therefore, on date of adoption of ASC Topic 842, the Company recognized a ROU asset of $ 1.4 1.5 0.1 nd 0.4 1.8 1.9 0.1 Following is a table of the lease payments and maturity of our operating lease liabilities as of September 30, 2021: Schedule of Lease Payments and Maturity of Operating Lease Liabilities For the year ending Remainder of 2021 $ 149,573 2022 601,495 2023 238,609 2024 and thereafter - Subtotal future lease payments 989,677 Less imputed interest (81,895 ) Total lease liabilities $ 907,782 Weighted average remaining life 1.7 Weighted average discount rate 8.28 % For the three-month and nine-month periods ended September 30, 2021, operating lease expense was $ 146,936 413,577 149,115 418,696 130,595 391,785 131,863 393,947

Technology Development and Lice

Technology Development and Licensing Agreements	9 Months Ended
	Sep. 30, 2021
Technology Development And Licensing Agreements
Technology Development and Licensing Agreements	Note 17. Technology Development and Licensing Agreements On May 7, 2012, the Company entered into a long-term commercial supply agreement with Zhejiang Hisun Pharmaceutical Co. Ltd. (Hisun) for the production of ThermoDox ® ® ® ® ® ® On January 18, 2013, we entered into a technology development contract with Hisun, pursuant to which Hisun paid us a non-refundable research and development fee of $ 5 ® ® ® 5.0 10 ® On July 19, 2013, the Company and Hisun entered into a Memorandum of Understanding to pursue ongoing cooperation for the continued clinical development of ThermoDox ® ® Among the key provisions of the Celsion-Hisun Memorandum of Understanding are: ● Hisun will provide the Company with internal resources necessary to complete the technology transfer of the Company’s proprietary manufacturing process and the production of registration batches for the China territory; ● Hisun will coordinate with the Company around the clinical and regulatory approval activities for ThermoDox ® ● Hisun will be granted a right of first ® ® On August 8, 2016, we signed a Technology Transfer, Manufacturing and Commercial Supply Agreement (“GEN-1 Agreement”) with Hisun to pursue an expanded partnership for the technology transfer relating to the clinical and commercial manufacture and supply of GEN-1, Celsion’s proprietary gene mediated, IL-12 immunotherapy, for the greater China territory, with the option to expand into other countries in the rest of the world after all necessary regulatory approvals are in effect. The GEN-1 Agreement will help to support supply for both ongoing and planned clinical studies in the U.S., and for potential future studies of GEN-1 in China. GEN-1 is currently being evaluated by Celsion in first line ovarian cancer patients. Key provisions of the GEN-1 Agreement are as follows: ● the GEN-1 Agreement has targeted unit costs for clinical supplies of GEN-1 that are substantially competitive with the Company’s current suppliers; ● once approved, the cost structure for GEN-1 will support rapid market adoption and significant gross margins across global markets; ● Celsion will provide Hisun a certain percentage of China’s commercial unit demand, and separately of global commercial unit demand, subject to regulatory approval; ● Hisun and Celsion will commence technology transfer activities relating to the manufacture of GEN-1, including all studies required by CHINA FDA for site approval; and ● Hisun will collaborate with Celsion around the regulatory approval activities for GEN-1 with the CHINA FDA. A local China partner affords Celsion access to accelerated CHINA FDA review and potential regulatory exclusivity for the approved indication. The Company evaluated the Hisun arrangement in accordance with ASC 606 and determined that its performance obligations under the agreement include the non-exclusive, royalty-free license, research and development services to be provided by the Company, and its obligation to serve on a joint committee. The Company concluded that the license was not distinct since its value is closely tied to the ongoing research and development activities. As such, the license and the research and development services are bundled as a single performance obligation. Since the provision of the license and research and development services are considered a single performance obligation, the $ 5,000,000

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 18. Commitments and Contingencies On September 20, 2019, a purported stockholder of the Company filed a derivative and putative class action lawsuit against the Company and certain officers and directors (the “Shareholder Action”). The Company was a defendant in this derivative and putative class action lawsuit in the Superior Court of New Jersey, Chancery Division, filed by a shareholder against the Company (as both a class action defendant and nominal defendant), and certain of its officers and directors (the “Individual Defendants”), with the caption O’Connor v. Braun et al., Docket No. MER-C-000068-19 On April 24, 2020, the Company, the Individual Defendants, and the plaintiff (the “Parties”) entered into a Settlement Agreement and Release (the “Settlement Agreement”), which memorializes the terms of the Parties’ settlement of the Shareholder Action (the “Settlement”). The Settlement calls for repricing of certain stock options and payment of plaintiff legal fees of $ 187,500 187,500 On October 29, 2020, a putative securities class action was filed against the Company and certain of its officers and directors (the “Spar Individual Defendants”) in the U.S. District Court for the District of New Jersey, captioned Spar v. Celsion Corporation, et al. ® In February 2021, a derivative shareholder lawsuit was filed against the Company, as the nominal defendant, and certain of its directors and officers as defendants in the U.S. District Court for the District of New Jersey, captioned Fidler v. Michael H. Tardugno et al. ®. In August of 2021, a complaint regarding a corporate books and records demand was filed against the Company in the Court of Chancery of the State of Delaware, captioned Pacheco v. Celsion Corporation

Restricted Cash (Tables)

Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Schedule of Cash and Cash Equivalents and Restricted Cash	The following table reconciles cash and cash equivalents and restricted cash per the balance sheet to the condensed statements of cash flows: Schedule of Cash and Cash Equivalents and Restricted Cash September 30, 2021 September 30, 2020 Cash and cash equivalents $ 25,648,849 $ 18,339,728 Money market investments, restricted 6,000,000 - Total $ 31,648,849 $ 18,339,728

Investment in Debt Securities_2

Investment in Debt Securities-Available for Sale (Tables)	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Schedule of Cost, Fair Value and Maturities of Short Term Investments	A summary of the cost, fair value and maturities of the Company’s short-term investments is as follows: Schedule of Cost, Fair Value and Maturities of Short Term Investments September 30, 2021 December 31, 2020 Cost Fair Value Cost Fair Value Short-term investments Commercial paper $ 7,784,165 $ 7,784,894 $ - - Government backed debt securities 21,078,059 21,079,470 - - Total $ 28,862,224 $ 28,864,364 $ - $ - September 30, 2021 December 31, 2020 Cost Fair Value Cost Fair Value Short-term investment maturities Within 3 months $ 11,998,304 $ 11,999,400 $ - $ - Between 3-12 months 16,863,920 16,864,964 - - Total $ 28,862,224 $ 28,864,364 $ - $ -
Summary of Investment Securities Gross Unrealized Gains (Losses)	The following table shows the Company’s investment in debt securities available for sale gross unrealized gains (losses) and fair value by investment category and length of time that individual securities have been in a continuous unrealized loss position at September 30, 2021 and December 31, 2020. The Company has reviewed individual securities to determine whether a decline in fair value below the amortizable cost basis is other than temporary. Summary of Investment Securities Gross Unrealized Gains (Losses) September 30, 2021 December 31, 2020 Available for sale securities (all unrealized holding gains and losses are less than 12 months at date of measurement) Fair Value Unrealized Holding Gains (Losses) Fair Value Unrealized Holding Gains (Losses) Investments with unrealized gains $ 21,029,520 $ 3,055 $ - $ - Investments with unrealized losses 7,834,844 (916 ) - - Total $ 28,864,364 $ 2,139 $ - $ -
Summary of Net Realized Losses on Sales of Available for Sale Securities and Investment Income Interest and Dividends	Investment (loss) income, which includes net realized losses on sales of available for sale securities and investment income interest and dividends, is summarized as follows: Summary of Net Realized Losses on Sales of Available for Sale Securities and Investment Income Interest and Dividends 2021 2020 Three Months Ended September 30, 2021 2020 Interest and dividends accrued and paid $ 6,288 $ 2,857 Realized (losses) gains (2,736 ) 7,257 Investment income, net $ 3,552 $ 10,114 2021 2020 Nine Months Ended September 30, 2021 2020 Interest and dividends accrued and paid $ 10,135 $ 66,029 Realized (losses) gains (4,521 ) 53,354 Investment income, net $ 5,614 $ 119,383

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Measurements
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Assets and liabilities measured at fair value are summarized below: Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Total Fair Value Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Recurring items as of September 30, 2021 Investment in debt securities - available for sale, at fair value $ 28,864,364 $ – $ 28,864,364 $ – Non-recurring items as of September 30, 2021 In-process R&D (Note 9) $ 13,366,234 $ – $ – $ 13,366,234 Non-recurring items as of December 31, 2020 In-process R&D (Note 9) $ 13,366,234 $ – $ – $ 13,366,234 Liabilities: Recurring items as of September 30, 2021 Earn-out milestone liability (Note 14) $ 7,345,000 $ – $ – $ 7,345,000 Recurring items as of December 31, 2020 Earn-out milestone liability (Note 14) $ 7,018,000 $ – $ – $ 7,018,000

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Fair Value of Assets Acquired	Following is a summary of the net fair value of the assets acquired in the EGEN asset acquisition for the nine-month period ended September 30, 2021: Schedule of Fair Value of Assets Acquired IPR&D Goodwill Covenant Not To Compete For the nine-months ended September 30, 2021 Balance at January 1, 2021, net $ 13,366,234 $ 1,976,101 $ 113,660 Amortization - - (113,660 ) Balance at September 30, 2021, net $ 13,366,234 $ 1,976,101 $ -

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Other accrued liabilities at September 30, 2021 and December 31, 2020 include the following: Schedule of Accrued Liabilities September 30, 2021 December 31, 2020 Amounts due to contract research organizations and other contractual agreements $ 1,276,317 $ 636,000 Accrued payroll and related benefits 1,247,460 1,736,271 Accrued professional fees 265,350 66,850 Accrued interest 16,250 - Other 19,411 19,411 Total $ 2,824,788 $ 2,458,532

Notes Payable (Tables)

Notes Payable (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Future Principle Payments, Net of Unamortized Debt Discounts	Following is a schedule of future principal payments, net of unamortized debt discounts and amortized end-of-term fee, due on the SVB Loan Facility: Schedule of Future Principle Payments, Net of Unamortized Debt Discounts As of September 30, 2022 $ – 2023 750,000 2024 3,000,000 2025 and thereafter 2,250,000 Subtotal of future principal payments 6,000,000 Unamortized debt premium, net (191,226 ) Total $ 5,808,774
Schedule of Debt	On June 18, 2021, as a condition of entering into the SVB Loan Facility, the Company paid the outstanding principal balance, an early termination fee and the end of term charges in full satisfaction of the Horizon Credit Agreement, as amended. Following is a schedule of the amounts paid to Horizon on June 18, 2021. Schedule of Debt Principal balance at June 18, 2021 $ 5,000,000 Early termination fees 150,000 End of term charges 275,000 Total $ 5,425,000

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary of Stock Option Awards and Restricted Stock Grants	A summary of stock option awards and restricted stock grants for the nine-months ended September 30, 2021 is presented below: Summary of Stock Option Awards and Restricted Stock Grants Stock Options Restricted Stock Awards Weighted Average Options Outstanding Weighted Average Exercise Price Non-vested Restricted Stock Outstanding Weighted Average Grant Date Fair Value Contractual Terms of Equity Awards (in years) Equity awards outstanding at January 1, 2021 4,624,725 $ 2.77 2,750 $ 0.89 Equity awards granted 2,171,250 $ 2.17 9,000 $ 1.29 Equity awards exercised or vested and issued (7,500 ) $ 0.63 - $ - Equity awards forfeited, cancelled or expired (185,770 ) $ 2.59 (1,000 ) $ 2.22 Equity awards outstanding at September 30, 2021 6,602,705 $ 2.58 10,750 $ 1.33 7.8 Aggregate intrinsic value of outstanding equity awards at September 30, 2021 $ 2,538 $ 12,383 Equity awards exercisable at September 30, 2021 4,291,685 $ 2.73 7.2 Aggregate intrinsic value of equity awards exercisable at September 30, 2021 $ -
Schedule of Assumptions Used to Determine Fair Value of Options Granted	The fair values of stock options granted were estimated at the date of grant using the Black-Scholes option pricing model. The Black-Scholes model was originally developed for use in estimating the fair value of traded options, which have different characteristics from Celsion’s stock options. The model is also sensitive to changes in assumptions, which can materially affect the fair value estimate. The Company used the following assumptions for determining the fair value of options granted under the Black-Scholes option pricing model: Schedule of Assumptions Used to Determine Fair Value of Options Granted Nine Months Ended 2021 2020 Risk-free interest rate 1.54 1.74 % 0.66 1.33 % Expected volatility 106.8 113.2 % 100.4 104.8 % Expected life (in years) 7.5 10.0 8.0 10.0 Expected dividend yield - % - %

Earn-Out Milestone Liability (T

Earn-Out Milestone Liability (Tables)	9 Months Ended
	Sep. 30, 2021
Earn-out Milestone Liability
Schedule of Changes in Earn-out Milestone Liability	The following is a summary of the changes in the earn-out milestone liability for the nine-month period ended September 30, 2021: Schedule of Changes in Earn-out Milestone Liability Balance at January 1, 2021 $ (7,018,000 ) Non-cash loss from the change in fair value (327,000 ) Balance at September 30, 2021 $ (7,345,000 )
Schedule of Risk Adjustment Assessment	The following is a schedule of the Company’s risk-adjustment assessment of each milestone: Schedule of Risk Adjustment Assessment Date Risk-adjustment Assessment of Achieving Each Milestone Discount Rate Estimated Time to Achieve September 30, 2021 80 % 6.54 6.60 % 0.29 1.29 June 30, 2021 80 % 9 % 0.42 1.42 December 31, 2020 80 % 9 % 0.54 1.54 September 30, 2020 80 % 9 % 0.38 1.38 June 30, 2020 80 % 9 % 0.54 1.54 December 31, 2019 80 % 9 % 1.12 2.12

Warrants (Tables)

Warrants (Tables)	9 Months Ended
	Sep. 30, 2021
Warrants
Summary of Warrant Activity	Following is a summary of all warrant activity for the nine-months ended September 30, 2021: Summary of Warrant Activity Warrants Number of Issued Weighted Average Exercise Price Warrants outstanding at December 31, 2020 3,853,566 $ 1.35 Warrants exercised during the nine months ended September 30, 2021 (see Note 12) (1,216,667 ) $ 1.24 Warrants outstanding at September 30, 2021 2,636,899 $ 1.40 Aggregate intrinsic value of outstanding warrants at September 30, 2021 $ 159,857 Weighted average remaining contractual terms at September 30, 2021 4.1

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases
Schedule of Lease Payments and Maturity of Operating Lease Liabilities	Following is a table of the lease payments and maturity of our operating lease liabilities as of September 30, 2021: Schedule of Lease Payments and Maturity of Operating Lease Liabilities For the year ending Remainder of 2021 $ 149,573 2022 601,495 2023 238,609 2024 and thereafter - Subtotal future lease payments 989,677 Less imputed interest (81,895 ) Total lease liabilities $ 907,782 Weighted average remaining life 1.7 Weighted average discount rate 8.28 %

Financial Condition and Busin_2

Financial Condition and Business Plan (Details Narrative) - USD ($)

Jun. 16, 2021

Mar. 19, 2021

Aug. 28, 2020

Jun. 18, 2021

Jan. 31, 2021

Sep. 30, 2020

Jun. 30, 2018

Sep. 30, 2021

Sep. 29, 2021

Dec. 31, 2019

Dec. 31, 2018

Apr. 05, 2021

Dec. 31, 2020

Sep. 30, 2018

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Cumulative net losses

$ 328,548,285

$ 312,000,341

Cash and cash equivalents, restricted cash, short-term investments, interest receivable

60,600,000

Receivable on sale of net operating losses

$ 1,850,000

Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Proceeds from Contributed Capital

$ 10,000,000

Debt Instrument, Face Amount

$ 10,000,000

Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] | London Interbank Offered Rate (LIBOR) [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Debt Instrument, Interest Rate, Stated Percentage

7.625%

SVB Loan Facility [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Debt Instrument, Description

Payments under the loan agreement are interest only for the first 24 months after loan closing, followed by a 24-month amortization period of principal and interest through the scheduled maturity date.

Payments under the loan agreement are interest only (calculated based on one-month LIBOR plus 7.625%) for the first 24 months through July 2020, followed by a 21-month amortization period of principal and interest starting on August 1, 2020 and ending through the scheduled maturity date

Debt Instrument, Interest Rate, Stated Percentage

3.25%

Line of Credit Facility, Maximum Borrowing Capacity

$ 10,000,000

Line of Credit Facility, Remaining Borrowing Capacity

$ 4,000,000

SVB Loan Facility [Member] | Silicon Valley Bank [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Line of Credit Facility, Maximum Borrowing Capacity

$ 10,000,000

Line of Credit Facility, Remaining Borrowing Capacity

$ 4,000,000

SVB Loan Facility [Member] | Prime Rate [Member] | Silicon Valley Bank [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Debt Instrument, Interest Rate, Stated Percentage

3.25%

SVB Loan Facility [Member] | Horizon Technology Finance Corporation [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Repayment of outstanding in-debtedness amount

$ 6,000,000

Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Repayments of Notes Payable

5,000,000

Debt Instrument, Face Amount

5,000,000

Debt instrument related end term charges

$ 200,000

Capital on DemandTM Sales Agreement [Member] | Jones Trading Institutional Services, LLC [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Cash and cash equivalents, restricted cash, short-term investments, interest receivable

60,600,000

Proceeds from Contributed Capital

$ 6,900,000

Debt Instrument, Face Amount

$ 35,000,000

$ 15,000,000

Proceeds from Warrant Exercises

$ 1,500,000

New Jersey [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Net proceeds from sale of net operating losses

$ 1,600,000

$ 2,000,000

$ 20,000,000

$ 15,000,000

$ 12,200,000

$ 13,000,000

New Jersey [Member] | Maximum [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Net proceeds from sale of net operating losses

$ 1,400,000

Schedule of Cash and Cash Equiv

Schedule of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Receivables [Abstract]
Cash and cash equivalents	$ 25,648,849	$ 17,164,177	$ 18,339,728
Money market investments, restricted	6,000,000
Total	$ 31,648,849		$ 18,339,728

Restricted Cash (Details Narrat

Restricted Cash (Details Narrative) - USD ($)	1 Months Ended
	Jun. 18, 2021	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Restricted Investments		$ 6,000,000
SVB Loan Facility [Member]
Defined Benefit Plan Disclosure [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 10,000,000
Line of Credit Facility, Description	the Company is required at all times to maintain on deposit with SVB as cash collateral in a segregated money market bank account in the name of the Company, unrestricted and unencumbered cash (other than a lien in favor of SVB) in an amount of at least 100% of the aggregate outstanding amount of the SVB loan facility. SVB may restrict withdrawals or transfers by or on behalf of the Company that would violate this requirement.
Silicon Valley Bank [Member] | SVB Loan Facility [Member]
Defined Benefit Plan Disclosure [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		10,000,000
Restricted Investments		$ 6,000,000

Net Loss per Common Share (Deta

Net Loss per Common Share (Details Narrative) - $ / shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Shares of common stock issuable upon exercise of warrants and equity awards	9,250,354	8,507,041
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.01
Number of shares of common stock issued in calculation basic loss per share		200,000

Schedule of Cost, Fair Value an

Schedule of Cost, Fair Value and Maturities of Short Term Investments (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Dec. 30, 2020
Marketable Securities [Line Items]
Short-term investment maturities - Between 3-12 months, cost	$ 28,862,224
Short-term investment maturities - Between 3-12 months, fair value	28,864,364
Short-term investment maturities - Within 3 months, cost	11,998,304
Short-term investment maturities - Within 3 months, fair value	11,999,400
Short-term investment maturities - Between 3-12 months, cost	16,863,920
Short-term investment maturities - Between 3-12 months, fair value	16,864,964
Total, cost	28,862,224
Total, fair value	28,864,364
Commercial Paper [Member]
Marketable Securities [Line Items]
Short-term investment maturities - Between 3-12 months, cost	7,784,165
Short-term investment maturities - Between 3-12 months, fair value	7,784,894
Government Backed Debt Securities [Member]
Marketable Securities [Line Items]
Short-term investment maturities - Between 3-12 months, cost	21,078,059
Short-term investment maturities - Between 3-12 months, fair value	$ 21,079,470

Summary of Investment Securitie

Summary of Investment Securities Gross Unrealized Gains (Losses) (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments with unrealized gains, Fair Value	$ 21,029,520
Investments with unrealized gains, Unrealized Holding Gains (Losses)	3,055
Investments with unrealized losses, Fair Value	7,834,844
Investments with unrealized Losses, Unrealized Holding Gains (Losses)	(916)
Investment securities, available for sale	28,864,364
Investments with unrealized Gains (Losses), Unrealized Holding Gains (Losses)	$ 2,139

Summary of Net Realized Losses

Summary of Net Realized Losses on Sales of Available for Sale Securities and Investment Income Interest and Dividends (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Interest and dividends accrued and paid	$ 6,288	$ 2,857	$ 10,135	$ 66,029
Realized (losses) gains	(2,736)	7,257	(4,521)	53,354
Investment income, net	$ 3,552	$ 10,114	$ 5,614	$ 119,383

Investment in Debt Securities_3

Investment in Debt Securities-Available for Sale (Details Narrative) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investment in debt securities - available for sale, at fair value	$ 28,864,364

Schedule of Fair Value, Assets

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale	$ 28,864,364
Earn-out milestone liability	7,345,000	7,018,000
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earn-out milestone liability	7,345,000	7,018,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earn-out milestone liability
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earn-out milestone liability
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earn-out milestone liability	7,345,000	7,018,000
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale	28,864,364
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale	28,864,364
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale
Fair Value, Nonrecurring [Member] | Inprocess R&D [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale	13,366,234	13,366,234
Fair Value, Nonrecurring [Member] | Inprocess R&D [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale
Fair Value, Nonrecurring [Member] | Inprocess R&D [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale
Fair Value, Nonrecurring [Member] | Inprocess R&D [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities, available for sale	$ 13,366,234	$ 13,366,234

Schedule of Fair Value of Asset

Schedule of Fair Value of Assets Acquired (Details)	9 Months Ended
	Sep. 30, 2021USD ($)
Finite-Lived Intangible Assets [Line Items]
Intangible assets, beginning balance	$ 113,660
Intangible assets, ending balance
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, beginning balance	113,660
Amortization	(113,660)
Intangible assets, ending balance
IPR and D [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, beginning balance	13,366,234
Amortization
Intangible assets, ending balance	13,366,234
Goodwill [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, beginning balance	1,976,101
Amortization
Intangible assets, ending balance	$ 1,976,101

Intangible Assets (Details Narr

Intangible Assets (Details Narrative) - USD ($)	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Finite-Lived Intangible Assets, Net									$ 113,660
2018 Aspire Purchase Agreements [Member]
Restructuring Cost and Reserve [Line Items]
Finite-Lived Intangible Assets, Net									113,660
Finite-Lived Intangible Assets, Accumulated Amortization									$ 1,477,554
Glioblastoma Multiforme Brain Cancer [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges							$ 2,400,000
IPR and D Drug Technology Platforms [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges		$ 0	$ 0		0	$ 0
IPR and D Drug Technology Platforms [Member] | Ovarian Cancer [Member]
Restructuring Cost and Reserve [Line Items]
Finite-lived Intangible Assets Acquired					13,300,000
EGEN Inc [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges								$ 7,000,000
Goodwill, Acquired During Period					2,000,000
EGEN Inc [Member] | Purchase Agreement [Member]
Restructuring Cost and Reserve [Line Items]
Finite-lived Intangible Assets Acquired					$ 1,600,000
Finite-Lived Intangible Asset, Useful Life					7 years
Amortization			56,830	$ 113,660		$ 170,487
EGEN Inc [Member] | Glioblastoma Multiforme Brain Cancer [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges	$ 2,400,000							$ 9,400,000
Noncash Charge			$ 2,400,000
EGEN Inc [Member] | IPR and D Drug Technology Platforms [Member]
Restructuring Cost and Reserve [Line Items]
Indefinite-lived Intangible Assets Acquired					$ 24,200,000

Schedule of Accrued Liabilities

Schedule of Accrued Liabilities (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Amounts due to contract research organizations and other contractual agreements	$ 1,276,317	$ 636,000
Accrued payroll and related benefits	1,247,460	1,736,271
Accrued professional fees	265,350	66,850
Accrued interest	16,250
Other	19,411	19,411
Total	$ 2,824,788	$ 2,458,532

Schedule of Future Principle Pa

Schedule of Future Principle Payments, Net of Unamortized Debt Discounts (Details)	Sep. 30, 2021USD ($)
Debt Disclosure [Abstract]
2022
2023	750,000
2024	3,000,000
2025 and thereafter	2,250,000
Subtotal of future principal payments	6,000,000
Unamortized debt premium, net	(191,226)
Total	$ 5,808,774

Schedule of Debt (Details)

Schedule of Debt (Details) - Horizon Technology Finance Corporation [Member]	Jun. 18, 2021USD ($)
Principal balance at June 18, 2021	$ 5,000,000
Early termination fees	150,000
End of term charges	275,000
Total	$ 5,425,000

Notes Payable (Details Narrativ

Notes Payable (Details Narrative) - USD ($)	Aug. 28, 2020	Jun. 27, 2018	Jun. 18, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021
Short-term Debt [Line Items]
Interest and Debt Expense				$ 95,520	$ 450,732	$ 474,361	$ 1,130,699
Debt Issuance Costs, Net				$ 191,226		$ 191,226
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 0.01		$ 0.01
Initial Horizon Credit Agreement Amendment [Member]
Short-term Debt [Line Items]
Amortization of Debt Issuance Costs					251,993	$ 139,428	444,786
Interest Expense, Debt					$ 198,738	$ 225,920	$ 685,913
Horizon Technology Finance Corporation [Member]
Short-term Debt [Line Items]
Long-term Line of Credit			$ 5,425,000
SVB Loan Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			10,000,000
Proceeds from Lines of Credit			6,000,000
Restricted cash			6,000,000
Line of Credit Facility, Remaining Borrowing Capacity			$ 4,000,000
Debt Instrument, Interest Rate, Stated Percentage			3.25%
Final payment percentage			3.00%
Long-term Line of Credit			$ 10,000,000
Debt Instrument, Description			Payments under the loan agreement are interest only for the first 24 months after loan closing, followed by a 24-month amortization period of principal and interest through the scheduled maturity date.			Payments under the loan agreement are interest only (calculated based on one-month LIBOR plus 7.625%) for the first 24 months through July 2020, followed by a 21-month amortization period of principal and interest starting on August 1, 2020 and ending through the scheduled maturity date
Interest and Debt Expense			$ 243,370
End of term charge percentage			3.00%
Amortization of Debt Issuance Costs			$ 300,000
Interest Expense, Debt				$ 49,883		$ 56,875
Amortization of Debt Issuance Costs and Discounts				$ 45,687		52,144
Initial Horizon Credit Agreement [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 10,000,000
Proceeds from Lines of Credit		10,000,000
Line of Credit Facility, Remaining Borrowing Capacity		5,000,000
Interest and Debt Expense		$ 175,000
End of term charge percentage		4.00%
Debt Instrument, Fee Amount		$ 142,605
Loan Processing Fee		100,000
Debt Instrument, Unamortized Discount		782,116
Debt Issuance Costs, Net		400,000
Fair Value Adjustment of Warrants		507,116
End of term fees		$ 275,000
Initial Horizon Credit Agreement [Member] | Common Stock [Member]
Short-term Debt [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		190,114
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 2.63
Class of Warrant or Right, Outstanding		95,057
Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member]
Short-term Debt [Line Items]
Debt instrument related end term charges	$ 200,000
Debt instrument face amount	$ 5,000,000
Debt Instrument, Interest Rate Terms	The obligations bore interest at a rate calculated based an amount by which the one-month LIBOR exceeds 2% plus 7.625%. In no event shall the interest rate be less than 9.625%. Payments pursuant to the Amendment were interest only for the first twelve (12) months after August 1, 2020, followed by a 21-month amortization period of principal and interest through the scheduled maturity date on April 1, 2023. In addition, the remaining $5 million in obligations was subject to an end of term fee equal, in the aggregate, to $275,000, which amount was payable upon the maturity of the obligations or upon the date of final payment or default, as applicable.
Payment for Debt Extinguishment or Debt Prepayment Cost	$ 5,000,000
Debt Instrument, Fee Amount	$ 275,000
Debt Instrument, Restrictive Covenants	In connection with the Amendment, Celsion agreed to a liquidity covenant which provides that, at all times, Celsion shall maintain unrestricted cash and/or cash equivalents on deposit in accounts over which the applicable Lenders maintain an account control agreement in an amount not less than $2.5 million. In addition, pursuant to the Amendment, Celsion agreed to provide evidence to Horizon on or before March 31, 2021, that it received aggregate cash proceeds of not less than $5 million from the sale of equity, debt, its New Jersey net operating losses, or a combination thereof, subsequent to the date of the Amendment. The Company met this requirement during the fourth quarter of 2020.
Debt Instrument, Unamortized Discount	$ 200,000							$ 109,706
Debt Issuance Costs, Net	5,000
Warrants Not Settleable in Cash, Fair Value Disclosure	$ 247,548
Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] | Common Stock [Member]
Short-term Debt [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	247,525
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 1.01
Warrants cancelled	95,057
Horizon Credit Agreement [Member]
Short-term Debt [Line Items]
Interest Expense, Debt						190,581
Gain (Loss) on Contract Termination						$ 234,419
Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member]
Short-term Debt [Line Items]
Debt instrument face amount	$ 10,000,000

Stockholders_ Equity (Details N

Stockholders’ Equity (Details Narrative) - USD ($)

Mar. 19, 2021

Jan. 22, 2021

Sep. 08, 2020

Jun. 22, 2020

Feb. 27, 2020

Dec. 04, 2018

Mar. 31, 2021

Sep. 30, 2018

Sep. 30, 2021

Sep. 30, 2020

Dec. 31, 2020

Jun. 30, 2021

Mar. 12, 2020

Accumulated Other Comprehensive Income (Loss) [Line Items]

Shelf registration statement amount

$ 100,000,000

$ 75,000,000

Proceeds from Issuance of Common Stock

$ 52,688,945

$ 20,250,426

Class of Warrant or Right, Exercise Price of Warrants or Rights

$ 0.01

Capital on DemandTM Sales Agreement [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Less than 12 months, unrealized gains, fair value

$ 16,000,000

Capital on Demand Agreement [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

7,200,000

2,100,000

Proceeds from Issuance of Common Stock

$ 6,900,000

$ 4,300,000

Securities Purchase Agreement [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

4,571,428

Proceeds from Issuance of Common Stock

$ 4,800,000

Shares Issued, Price Per Share

$ 1.05

Securities Purchase Agreement [Member] | Original Warrants [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Class of Warrant or Right, Number of Securities Called by Each Warrant or Right

2,971,428

Warrants and Rights Outstanding, Term

5 years

Class of Warrant or Right, Exercise Price of Warrants or Rights

$ 1.15

Exchange Agreements [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Class of Warrant or Right, Number of Securities Called by Each Warrant or Right

1,200,000

Proceeds from Issuance of Warrants

$ 1,500,000

Exchange Agreements [Member] | Warrant [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Class of Warrant or Right, Number of Securities Called by Each Warrant or Right

3,200,000

Warrants and Rights Outstanding, Term

5 years

Class of Warrant or Right, Exercise Price of Warrants or Rights

$ 1.24

Underwriting Agreement [Member] | Underwritten Offering [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

2,666,667

Proceeds from Issuance of Common Stock

$ 9,100,000

Shares Issued, Price Per Share

$ 3.75

Share Price

3.4875

[custom:UnderwritingDiscountPricePerShare]

$ 0.2625

Payments from sale of nols

7.00%

Underwriting Agreement [Member] | January 2021 Registered Direct Offering [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

25,925,925

Proceeds from Issuance of Common Stock

$ 35,000,000

Share Price

$ 1.35

Placement agent fee description.

In connection with the January 2021 Offering, the Company entered into a placement agent agreement (the “January 2021 Placement Agent Agreement”) with A.G.P./Alliance Global Partners (together with Brookline Capital Markets, the “January 2021 Placement Agents”) pursuant to which the Company agreed to pay the January 2021 Placement Agents a cash fee equal to 7% of the aggregate gross proceeds raised from the sale of the securities sold in the January 2021 Offering and reimburse the January 2021 Placement Agents for certain of their expenses in an amount not to exceed $82,500.

Underwriting Agreement [Member] | March 2021 Registered Direct Offering [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

11,538,462

Proceeds from Issuance of Common Stock

$ 15,000,000

Share Price

$ 1.30

Placement agent fee description.

In connection with the March 2021 Offering, the Company entered into a placement agent agreement (the “March 2021 Placement Agent Agreement”) with A.G.P./Alliance Global Partners, as lead placement agent (“AGP,” and together with JonesTrading Institutional Services LLC and Brookline Capital Markets, a division of Arcadia Securities, LLC, serving as co-placement agents, the “March 2021 Placement Agents”), pursuant to which the Company agreed to pay the March 2021 Placement Agents an aggregate cash fee equal to 7% of the aggregate gross proceeds raised from the sale of the securities sold in the Offering and reimburse the Placement Agents for certain of their expenses in an amount not to exceed $82,500.

LPC Purchase Agreement [Member] | Lincoln Park Capital Fund, LLC [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

26,000,000

3,300,000

Proceeds from Issuance of Common Stock

$ 2,200,000

LPC Purchase Agreement [Member] | LPC Commitment Shares [Member] | Lincoln Park Capital Fund, LLC [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Stock Issued During Period, Shares, New Issues

437,828

Summary of Stock Option Awards

Summary of Stock Option Awards and Restricted Stock Grants (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Exercise Price, Options granted	$ 1.97	$ 3.07
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding, Outstanding, Beginning balance	4,624,725
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 2.77
Number Outstanding, Options granted	2,171,250
Weighted Average Exercise Price, Options granted	$ 2.17
Number Outstanding, Options exercised or vested and issued	(7,500)
Weighted Average Exercise Price, Options exercised or vested and issued	$ 0.63
Number Outstanding, Options canceled or expired	(185,770)
Weighted Average Exercise Price, Options canceled or expired	$ 2.59
Number Outstanding, Outstanding, Ending balance	6,602,705
Weighted Average Exercise Price, Outstanding, Ending balance	$ 2.58
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 9 months 18 days
Aggregate Intrinsic Value, Outstanding, Ending balance	$ 2,538
Number Outstanding, Exercisable, Ending balance	4,291,685
Weighted Average Exercise Price, Exercisable, Ending balance	$ 2.73
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 2 months 12 days
Aggregate Intrinsic Value, Exercisable, Ending balance
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding, Non-vested stock awards, Outstanding, Beginning balance	2,750
Weighted Average Grant Date Fair Value, Non-vested stock awards, Outstanding, Beginning balance	$ 0.89
Number Outstanding, Non-vested stock awards, Granted	9,000
Weighted Average Grant Date Fair Value, Non-vested stock awards, Granted	$ 1.29
Number Outstanding, Non-vested stock awards, exercised or vested and issued
Weighted Average Grant Date Fair Value, Non-vested stock awards, exercised or vested and issued
Number Outstanding, Non-vested stock awards, Forfeited	(1,000)
Weighted Average Grant Date Fair Value, Non-vested stock awards, Forfeited	$ 2.22
Number Outstanding, Non-vested stock awards, Outstanding, Ending balance	10,750
Weighted Average Grant Date Fair Value, Non-vested stock awards, Outstanding, Ending balance	$ 1.33
Aggregate Intrinsic Value, Non-vested stock awards, Outstanding, Ending balance	$ 12,383

Schedule of Assumptions Used to

Schedule of Assumptions Used to Determine Fair Value of Options Granted (Details)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum	1.54%	0.66%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum	1.74%	1.33%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum	106.80%	100.40%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	113.20%	104.80%
Expected dividend yield
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	7 years 6 months	8 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	10 years	10 years

Stock-Based Compensation (Detai

Stock-Based Compensation (Details Narrative) - USD ($)	Feb. 19, 2019	Sep. 28, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 10, 2021	Jun. 15, 2020	May 14, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price					$ 1.97	$ 3.07
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount			$ 2,400,000		$ 2,400,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition					1 year
Equity Stock Awards [Member] | Granted Under 2018 Plan and 2007 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance			6,473,451		6,473,451
Inducement Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance			140,004		140,004
Stock Options and Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense			$ 700,624	$ 417,476	$ 3,073,569	$ 1,448,202
Stock Options and Restricted Stock Awards [Member] | Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense			241,288	164,035	1,123,376	542,157
Stock Options and Restricted Stock Awards [Member] | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense			$ 459,336	$ 253,441	$ 1,950,193	$ 906,045
2018 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized			2,700,000		2,700,000
Common Stock, Capital Shares Reserved for Future Issuance			14,198,424		14,198,424
2018 Stock Incentive Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant							7,700,000	2,500,000	1,200,000
2018 Stock Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant							14,100,000	6,400,000	3,900,000
2007 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, strike price description					Options are generally granted with strike prices equal to the fair market value of a share of Celsion common stock on the date of grant. Incentive stock options may be granted to purchase shares of common stock at a price not less than 100% of the fair market value of the underlying shares on the date of grant, provided that the exercise price of any incentive stock option granted to an eligible employee owning more than 10% of the outstanding stock of Celsion must be at least 110% of such fair market value on the date of grant. Only officers and key employees may receive incentive stock options.
Inducement Option Grants [Member] | Five New Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 2.18	$ 2.77
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Inducement Option Grants [Member] | Five New Employees [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Issued	13,000	19,000
Inducement Option Grants [Member] | Five New Employees [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Issued	140,004	164,004
2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance			7,724,973		7,724,973

Schedule of Changes in Earn-out

Schedule of Changes in Earn-out Milestone Liability (Details)	9 Months Ended
	Sep. 30, 2021USD ($)
Earn-out Milestone Liability
Earn-out liabilities, beginning balance	$ (7,018,000)
Non-cash gain loss from the adjustment for the change in fair value	(327,000)
Earn-out liabilities, ending balance	$ (7,345,000)

Schedule of Risk Adjustment Ass

Schedule of Risk Adjustment Assessment (Details)	6 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Risk-adjustment Assessment of achieving each Milestone	80.00%	80.00%	80.00%	80.00%	80.00%	80.00%
Discount Rate	9.00%	9.00%		9.00%	9.00%	9.00%
Minimum [Member]
Discount Rate			6.54%
Estimated time to achieve mile stone	5 months 1 day	6 months 14 days	3 months 14 days	4 months 17 days	6 months 14 days	1 year 1 month 13 days
Maximum [Member]
Discount Rate			6.60%
Estimated time to achieve mile stone	1 year 5 months 1 day	1 year 6 months 14 days	1 year 3 months 14 days	1 year 4 months 17 days	1 year 6 months 14 days	2 years 1 month 13 days

Earn-Out Milestone Liability (D

Earn-Out Milestone Liability (Details Narrative) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Mar. 28, 2019
EGWC, Inc [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-cash charge on earnout milestone liability	$ 0.3	$ 1.1			$ 0.3	$ 1.4
Earnout payment options description					In assessing the earnout milestone liability at September 30, 2021 and June 30, 2021, the Company determined the fair value of each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 50% and 50% probability for the $7.0 million and the $12.4 million payments, respectively.	In assessing the earnout milestone liability at September 30, 2020, the Company fair valued each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 50% and 50% probability for the $7.0 million and the $12.4 million payments, respectively, and at June 30, 2020, the Company determined the fair value of each of the two payment options per the Amended Asset Purchase Agreement and weighted them at 80% and 20% probability for the $7.0 million and the $12.4 million payments, respectively.
Amended Asset Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Earnout milestone liability									$ 12.4
Amended Asset Purchase Agreement [Member] | Within One Year of Achieving Milestone [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Earnout milestone liability									12.4
Amended Asset Purchase Agreement [Member] | 10 Business Days of Achieving Milestone [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Earnout milestone liability									$ 7
Fair Value Earnout Milestone Liability [Member] | EGWC, Inc [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Business Combination, Consideration Transferred, Liabilities Incurred			$ 7.1	$ 6	$ 7.3	$ 7.1	$ 7	$ 5.7

Summary of Warrant Activity (De

Summary of Warrant Activity (Details)	9 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares
Warrants
Number of Warrants Issued, Warrants outstanding, Beginning balance | shares	3,853,566
Weighted Average Exercise Price, Warrants outstanding, Beginning balance | $ / shares	$ 1.35
Number of Warrants Issued, Warrants exercised | shares	(1,216,667)
Weighted Average Exercise Price, Warrants exercised | $ / shares	$ 1.24
Number of Warrants Issued, Warrants outstanding, Ending balance | shares	2,636,899
Weighted Average Exercise Price, Warrants outstanding, Ending balance | $ / shares	$ 1.40
Aggregate intrinsic value of outstanding warrants | $	$ 159,857
Weighted average remaining contractual terms (years)	4 years 1 month 6 days

Schedule of Lease Payments and

Schedule of Lease Payments and Maturity of Operating Lease Liabilities (Details) - USD ($)	Sep. 30, 2021	Jan. 02, 2019
Leases
Remainder of 2021	$ 149,573
2022	601,495
2023	238,609
2024 and thereafter
Subtotal future lease payments	989,677
Less imputed interest	(81,895)
Total lease liabilities	$ 907,782	$ 1,900,000
Operating Lease, Weighted Average Remaining Lease Term	1 year 8 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent	8.28%

Leases (Details Narrative)

Leases (Details Narrative)	Jul. 09, 2021USD ($)ft²	Jan. 09, 2021	Jan. 02, 2019USD ($)	Jan. 31, 2018USD ($)	Jul. 31, 2011ft²	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)ft²
Lessee, Operating Lease, Description					In 2011, the Company executed a lease (the “Lease”) with Brandywine Operating Partnership, L.P. (Brandywine), a Delaware limited partnership, for a 10,870 square foot premises located in Lawrenceville, New Jersey and relocated its offices to Lawrenceville, New Jersey from Columbia, Maryland.
Area of Land | ft²					10,870
Lessee, Operating Lease, Term of Contract					66 months
Lease Expiration Date					Apr. 30, 2017
Operating Lease, Right-of-Use Asset			$ 400,000			$ 816,520		$ 816,520		$ 1,047,336
Operating Lease, Liability			1,900,000			907,782		907,782
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			1,800,000
Operating Lease, Payments								418,696	$ 393,947
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset			1,400,000
Operating Lease, Liability			1,500,000
Other Liabilities			$ 100,000
Accounting Standards Update 2021-01 [Member]
Operating Lease, Right-of-Use Asset						100,000		100,000
Operating Lease, Liability						100,000		100,000
Huntsville Alabama [Member]
Area of Land | ft²	2,197									11,500
1st Lease Amendment [Member]
Lessee, Operating Lease, Description		increase the size of the premises by 2,285 square feet to 9,850 square feet and also extended the lease term by one year to September 1, 2023
1st Lease Amendment [Member] | First Year [Member]
Payments for Rent								18,900
1st Lease Amendment [Member] | Final Year [Member]
Payments for Rent								20,500
2nd Lease Amendment [Member] | First Year [Member]
Payments for Rent								25,035
2nd Lease Amendment [Member] | Final Year [Member]
Payments for Rent								27,088
EGEN Asset Purchase Agreement [Member]
Lessee, Operating Lease, Description				In connection with the EGEN Asset Purchase Agreement in June 2014, the Company assumed the existing lease with another landlord for an 11,500 square foot premises located in Huntsville Alabama.
Payments for Rent	$ 5,500			$ 18,100
Operating Leases [Member]
Operating Lease, Cost						146,936	$ 130,595	413,577	391,785
Operating Lease, Payments						$ 149,115	$ 131,863	$ 418,696	$ 393,947

Technology Development and Li_2

Technology Development and Licensing Agreements (Details Narrative) - USD ($)	Jan. 18, 2013	Sep. 30, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Upfront payment being recognized		$ 5,000,000
Hisun [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from License Fees Received	$ 5,000,000
Deferred Revenue	$ 5,000,000
Deferred revenue amortization period	10 years

Commitments and Contingencies (

Commitments and Contingencies (Details Narrative) - USD ($)	Oct. 02, 2020	Apr. 24, 2020
Commitments and Contingencies Disclosure [Abstract]
Litigation Settlement, Expense		$ 187,500
Payments for Legal Settlements	$ 187,500