As filed with the Securities and Exchange Commission on January 4, 2016

June 27, 2019

Registration No. 333-208784________

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendement No. 1

to

Form S-3

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

CLEARSIGN COMBUSTION CORPORATION

(Exact Name of Registrant as Specified in Its Charter)

12870 Interurban Avenue South

Seattle, Washington 98168

(206) 673-4848

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Stephen E. PirnatColin James Deller

Chief Executive Officer

ClearSign Combustion Corporation

12870 Interurban Avenue South

Seattle, Washington 98168

(206) 673-4848

(Name, address, including zip code, and telephone number, including area code, of agent for service)

With copiesCopies to:

Kevin Friedmann,Mary Ann Sapone, Esq.

Mitchell Silberberg & Knupp LLP
11377 West Olympic Blvd.2049 Century Park East, 18^th Floor
Los Angeles, CA 9006490067

Telephone: (310) 312-3106312 3258

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement, as determined by market conditions and other factors.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ¨

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. x

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ¨

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer” andfiler,” “smaller reporting company” and "emerging growth company" in Rule 12b-2 of the Exchange Act.  (Check one):

CALCULATION OF REGISTRATION FEE

(1)The securities are being registered as an indeterminate number of securities that shall have an aggregate offering price not to exceed $50,000,000. This registration statement shall also cover any additional securities to be offered or issued from share splits, share dividends, recapitalizations or similar transactions.

(2) The proposed maximum offering price per unit will be determined from time to time by the registrant in connection with the issuance of securities.

(3) The proposed maximum aggregate offering price has been estimated for the sole purpose of computing the registration fee was paid on December 29, 2015.pursuant to Rule 457(o) under the Securities Act.

The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment that specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the Securities and Exchange Commission declares our registration statement effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to completion, dated June 27, 2019

PROSPECTUS

$50,000,000

Debt Securities, Common Stock, Preferred Stock, Warrants,

Units, and Subscription Rights Offered by

ClearSign Combustion Corporation

By this prospectus and an accompanying prospectus supplement, we may from time to time offer and sell, in one or more offerings, up to $50,000,000 in any combination of debt securities, common stock, preferred stock, warrants, units, or subscription rights.

We will provide you with more specific terms of the securities offered by us in one or more supplements to this prospectus. You should read this prospectus and the applicable prospectus supplement carefully before you invest.

We may offer these securities from time to time in amounts, at prices and on other terms to be determined at the time of offering. We may offer and sell these securities to or through underwriters, dealers or agents, or directly to investors, on a continuous or delayed basis.

The supplements to this prospectus will provide the specific terms of the plan of distribution. The price to the public of the securities we offer and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Our common stock is listed on the Nasdaq Capital Market under the symbol “CLIR”. On June 25, 2019, the closing price of our common stock as reported by the Nasdaq Capital Market was $1.0947 per share. The aggregate market value of our outstanding voting common stock held by non-affiliates, based upon a closing sale price of our common stock on June 25, 2019, was $23,403,762. During the 12 calendar month period that ends on, and includes, the date of this prospectus, we have not offered any securities pursuant to General Instruction I.B.6. of Form S-3.

An investment in our securities may be considered speculative and involves a high degree of risk, including the risk of a substantial loss of your investment. See “Risk Factors” on page 7 for more information on the risks you should consider before buying our securities. An investment in our securities is not suitable for all investors.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or passed upon the adequacy or accuracy of this prospectus.  Any representation to the contrary is a criminal offense.

The date of this prospectus is                      , 2019.

EXPLANATORY NOTETABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This Amendment No. 1 to Form S-3prospectus is part of a registration statement filed with the Securities and Exchange Commission (the “SEC”) using a “shelf” registration process. Under this shelf process, we may sell the securities described in this prospectus in one or more offerings. This prospectus provides you with a general description of the securities that may be offered. Each time we offer securities for sale, we will provide a prospectus supplement that contains specific information about the terms of that offering. Any prospectus supplement may also add or update information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with additional information described below under “Where You Can Find More Information” and “Information Incorporated by Reference.”

The registration statement that contains this prospectus (including the exhibits thereto) contains additional important information about us and the securities we may offer under this prospectus. Specifically, we have filed certain legal documents that establish the terms of the securities offered by this prospectus as exhibits to the registration statement. We will file certain other legal documents that establish the terms of the securities offered by this prospectus as exhibits to reports we file with the SEC. You may obtain copies of the registration statement and the other reports and documents referenced herein as described below under the heading “Where You Can Find More Information.”

You should rely only on the information contained or incorporated by reference in this prospectus and in any prospectus supplement. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not making offers to sell or solicitations to buy the securities in any jurisdiction in which an offer or solicitation is beingnot authorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should not assume that the information in this prospectus or any prospectus supplement, as well as the information we file or previously filed with the SEC that we incorporate by reference in this prospectus or any prospectus supplement, is accurate as of any date other than the date of such document. Our business, financial condition, results of operations and prospects may have changed since those dates.

In this prospectus, unless the context otherwise requires, references to “ClearSign,” “we,” “us,” “our” or the “Company” refer to ClearSign Combustion Corporation solelyand its subsidiary, ClearSign Asia Limited.

MARKET, INDUSTRY AND OTHER DATA

This prospectus, including the information incorporated by reference, contains estimates, projections and other information concerning our industry, our business, and the markets for certain products and services, including data regarding the purposeestimated size of addingthose markets and their projected growth rates. Information that is based on estimates, forecasts, projections or similar methodologies is based on a number of assumptions and is inherently subject to uncertainties, including those described in “Risk Factors” and elsewhere in this prospectus and documents incorporated by reference in this prospectus, and actual events or circumstances may differ materially from events and circumstances reflected in this information. You are cautioned not to give undue weight to such estimates, projections and other information.

DISCLOSURE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and any accompanying prospectus supplement, including the SEC file number (333-208784)documents that we incorporate by reference, may contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

Forward-looking statements in this prospectus and any accompanying prospectus supplement include, without limitation, statements related to our plans, strategies, objectives, expectations, intentions and adequacy of resources. Investors are cautioned that such forward-looking statements involve risks and uncertainties. Factors that could cause actual results to differ from those discussed in the consent, attachedforward-looking statements include, but are not limited to:

In some cases, you can identify forward-looking statements by terminology such as exhibit 23.1, provided by Gumbiner Savett Inc.‘‘may,’’ ‘‘will,’’ ‘‘should,’’ ‘‘could,’’ ‘‘expects,’’ ‘‘plans,’’ ‘‘intends,’’ ‘‘anticipates,’’ ‘‘believes,’’ ‘‘estimates,’’ ‘‘predicts,’’ ‘‘potential,’’ or ‘‘continue’’ or the negative of such terms or other comparable terminology. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee future results, levels of activity, performance or achievements. Readers are cautioned not to place undue reliance on December 29, 2015.these forward-looking statements, which speak only as of the date hereof. We do not undertake any obligation to publicly update or review any forward-looking statement.

OUR BUSINESS

This is only a summary and may not contain all the information that is important to you. You should carefully read both this prospectus and any accompanying prospectus supplement and any other offering materials, together with the additional information described under the heading “Where You Can Find More Information.”

About ClearSign Combustion Corporation

We design and develop technologies that have been shown to significantly improve key performance characteristics of combustion systems, including emission and operational performance, energy efficiency and overall cost-effectiveness. We believe that our patented Duplex™ technology can enhance the performance of combustion systems in a broad range of markets, including the energy (upstream oil production and down-stream refining), institutional commercial and industrial boiler, chemical, and petrochemical industries. Our Duplex technology, which is our primary technology, uses a porous ceramic matrix at a distance to a burner to significantly reduce flame length and achieve very low emissions without the need for external flue gas recirculation, selective catalytic reduction, or excess air systems. To date, our operations have been funded primarily through sales of our equity securities. We have earned nominal revenue since inception in 2008.

Duplex has been successfully installed in commercial projects across four different combustion applications. Based on the results of our testing and initial field installations, we believe that Duplex is more effective and cost-efficient than current industry-standard air pollution control technologies, such as selective catalytic reduction devices, low- and ultra-low NOx burners (which address nitrogen oxides or NOx), external flue gas recirculation systems and other similar technologies. Such systems are used in our current target market segments of petroleum refining and petrochemical process heaters, large-scale once through steam generators (OTSGs), enclosed flares, institutional commercial and industrial boilers and other similar equipment.

Based on the limited operating data we have obtained from installations, burners utilizing ClearSign’s ceramic Duplex technology provide increased heat transfer efficiency compared to standard burner designs. This is consistent with the physics of heat transfer and the mechanisms by which the ceramic technology functions. The increased heat transfer efficiency as reported results in cost savings in the low to mid-single digit range which produces an extremely attractive pay-back period for an investment in ClearSign technology-based burners. In addition, since the flames in a Duplex system are established within the confines of a ceramic enclosure and form with minimal “bulking up” from dilutive inert flue gasses, the flame volumes are small, thus virtually eliminating flame impingement and enabling the burners to function better in tightly spaced heaters. As a result, heaters utilizing ClearSign technology require less maintenance, operate at a lower cost, have increased productivity when heater operation is otherwise constrained by the internal furnace volume, and, more importantly, have decreased process downtime.

Our Industry

The combustion and emissions control markets are significant, both in the wide array of industries in which the systems are used and in the amount of money spent in installing and upgrading systems. Combustion systems are used to provide heat for all manner of industrial processes, including boilers, furnaces, kilns and gas turbines. In order to maximize energy efficiency while keeping pace with regulatory guidelines for air pollution emissions, operators of combustion systems are continually installing, maintaining and upgrading a variety of costly process control, air pollution control and monitoring systems. Although we believe that there are many potential markets for our Duplex technology, to date we have prioritized the introduction of Duplex to petroleum refining process heaters, steam generation, district heating and enclosed flares.

Our Proprietary Technology

Our Duplex burner technology consists of an industrial burner body and a downstream porous ceramic matrix. When the unreacted mix of gaseous fuel and air is directed at the ceramic matrix, the mixture ignites and stabilizes within the matrix itself. Because the fuel and air have more time to mix, the homogeneous mixture mitigates NOx-forming hot spots and chemistry that are typically produced. The mixing and combustion in the ceramic matrix results in a dramatically shorter flame, and modification of the matrix enables a high level of control over the shape of the flame allowing it to be optimized for a wide range of different applications. NOx, a regulated greenhouse gas pollutant comprised largely of nitrogen oxide and nitrogen dioxide, is greatly reduced to levels of 5ppm or below, depending on the specific application, without any external fans or associated power, thereby minimizing harmful emissions while improving system efficiency. A shorter flame can often allow for operation of the furnace at a higher capacity. We believe Duplex’s radiant heat transfer from the ceramic matrix enhances thermal efficiency, minimizes the possibility of flame impingement and reduces the likelihood of carbon deposits forming on the inside surfaces of the process tubes (coking) or failure of process tubes extending the length of time a heater can remain in operation before the need for maintenance.

Our Duplex Plug & Play® product provides a more simplified, pre-engineered and standardized direct burner replacement for traditional refinery process heaters. We believe that this product will reduce the customized engineering associated with typical retrofits and lend itself to mass production. The product derives its name from the fact that it is designed to allow quick and easy installation into a multi-burner heater or furnace and possibly allow the heater to continue operating during installation rather than be shut down. The ability to install the Duplex Plug & Play while the remaining burner system is operational will allow customers to limit down time and shorten the sales cycle often prolonged by annual or semi-annual scheduled maintenance.

To date, we have deployed our Duplex technology through retrofits and replacements of existing burners and complete replacement units in the case of our Plug & Play products. Retrofits often involve engineering around an existing burner architecture that can complicate the Duplex installation, whereas replacements are more straightforward and more amenable to being sold and installed by third parties, enabling more expansive channels to market. This is especially the case after the introduction of our Duplex Plug & Play technology in February 2017 and simplified control and operation in April 2019. Because of this, we have focused the development of our technology to provide designs that can be included into our customers’ equipment as self-contained modules or assemblies rather than as individual projects involving the re-engineering of existing burner systems. In this form, we believe that ClearSign burner technology is ideally suited for installation into new heaters and burner replacement markets, including heater and furnace types requiring large quantities of burners. We have also developed flare and boiler burner technology into a similar repeatable form to aid its inclusion in standard industry equipment on a commercial scale.

For simplification and marketing, we have adopted the term “ClearSign Coreä” to refer to the inclusion of this standardized Duplex technology into a variety of combustion systems including, but not limited to, burners, furnaces, boilers, heaters, thermal oxidizers and flares.

We have now achieved emission results in multiple applications that were superior to current local Best Available Control Technology (BACT) levels in multiple installations in California related to three of our five target industries. We intend to continue to demonstrate Duplex capabilities through (i) working with local air quality officials to demonstrate the effectiveness of the technology, (ii) operating in-place units, (iii) engineering and testing with new customers and applications, (iv) pursuing additional lab research and development of new applications (e.g. institutional commercial and industrial boilers) and next generation improvements to Duplex design and standardization, including the pursuit of more complete systems similar to the Duplex Plug & Play for application in other vertical markets, and (v) assisting our customers in making emission results available for designation as BACT by local regulatory bodies.

Business Model and Monetization Strategy

As described above, we have developed our Duplex technology into standardized configurations that can be incorporated into equipment sold by the major vendors in the industry in an effort to gain quick access to our large global markets and that for brand recognition and marketing purposes, we have named the inclusion of our technology into OEM equipment as the “ClearSign Coreä. This approach allows us to sell our technology business to business, through an arrangement similar to a license, to selected alliance companies which then manufacture and deliver the complete equipment to the final customers. The objective of this business model is to enable ClearSign to leverage our technology and the vast resources and networks of our supply partners to sell to the global markets. The details of such collaborative agreements will vary depending on the nature of the individual markets and requirements to achieve an optimum collaboration with our partners. At this time, we have entered into one such agreement and have received demonstrated interest in collaboration from other major equipment suppliers in all major verticals and target markets.

Our Target Markets

We compete in the combustion and emissions control markets. These are highly competitive industries that are currently dominated by companies that have both substantially greater infrastructure, customer support networks, and financial resources than we do as well as established products. Based on the testing and the field installations completed to date, however, we believe that our Duplex technology provides a unique and powerful ability to improve energy efficiency and operational performance, while at the same time significantly reducing emissions, leading to an overall cost-effective installation. Further, we believe that the ClearSign burner technology is well suited to create substantial synergistic value through its incorporation into the mainstream commercial offerings of the market incumbents as a “ClearSign Core,” thus leveraging the ClearSign technology and the established breadth and capabilities of collaborating companies.

We are targeting the following segments of the combustion market:

In each segment, we are marketing solutions with our Duplex technology that we believe could simultaneously improve both operational efficiency and pollution control characteristics through (a) cost-effective retrofitting of our Duplex technology into existing standard system designs, and (b) new system designs.

Our target markets are greatly affected by air emission regulations and economic conditions, including the price and profitability related to crude oil and its processing. We believe that operators in all of our target markets are under intense pressure to meet current and proposed federal, state and local emissions standards. The standards applicable to our target markets have been developed over the past 50 years with broad political input. Due to the localized effects of poor air quality, we anticipate these standards to continue regardless of national political leadership.

Emissions standards in the United States largely emanate from the Clean Air Act, which is administered by the Environmental Protection Agency (EPA) and regulates six common criteria air pollutants, including ground-level ozone. These regulations are enforced by state and local air quality districts as part of their compliance plans. As a precursor to ground-level ozone, NOx is a regulated pollutant by local air quality districts in order to achieve the EPA limits. The 8-hour ground-level ozone regulations have been reduced from 84 parts per billion (ppb) in 1997, to 75 ppb in 2008, and 70 ppb in 2015, with the requirement of realizing these levels approximately 25 years following the year of legislation. The areas of non-attainment related to this 1997 limit of 84 ppb are depicted below in the map on the left and the projected areas of non-attainment related to the 2015 limit of 70 ppb are depicted below in the map on the right.

Non-attainment areas under the 1997 limit of 84 ppb Source: EPA, August 2016		Projected non-attainment areas under the 2015 limit of 70 ppb Source: URS, August 2015

Additionally, we believe that current emissions standards in Europe, China, the Middle East, other parts of Asia and Canada will continue to trend towards stricter air emission standards as these jurisdictions seek to achieve cleaner air. Existing and new emissions standards in such jurisdictions may create additional market opportunities for us.

Additional Information

For a description of our business, financial condition, results of operations and other important information regarding us, we refer you to our filings with the SEC incorporated by reference in this prospectus supplement. For instructions on how to find copies of these documents, see “Where You Can Find More Information.”

Corporate Information

Our facilities and executive offices are located at 12870 Interurban Avenue South, Seattle, Washington 98168, and our telephone number is (206) 673-4848. We were incorporated in Washington on January 23, 2008. Additional information about us is available on our website at www.clearsign.com. The information contained on or that may be obtained from our website is not, and shall not be deemed to be, a part of this prospectus. Our common stock, par value $0.0001 per share, is currently traded on the Nasdaq Capital Market under the ticker symbol “CLIR.”

RISK FACTORS

Investing in our common stock involves a high degree of risk. Please see the risk factors set forth below and in Part I, Item 1A of our Annual Report on Form 10-K and Part II, Item 1A of our Quarterly Reports on Form 10-Q and other filings we make with the SEC, which are incorporated by reference in this prospectus. Additional risk factors may be included in a prospectus supplement relating to a particular offering of securities. Before making an investment decision, you should carefully consider these risks as well as other information we include or incorporate by reference in this prospectus. These risks could materially affect our business, results of operations or financial condition and cause the value of our securities to decline.

A cybersecurity incident or other technology disruptions could negatively impact our business and our relationships with customers.

We use computers in substantially all aspects of our business operations. We also use mobile devices and other online activities to connect with our employees, suppliers and customers. Such uses give rise to cybersecurity risks, including security breaches, espionage, system disruption, theft, the compromise of trade secrets and inadvertent release of information. Our business involves the storage and transmission of sensitive and/or confidential information and intellectual property, including customers’ and suppliers’ information, private information about employees and financial and strategic information about us. If we fail to assess and identify cybersecurity risks associated with our operations, we may become increasingly vulnerable to such risks. Additionally, while we have implemented measures to prevent security breaches and cyber incidents, our preventative measures and incident response efforts may not be entirely effective. The theft, destruction, loss, misappropriation, or release of sensitive and/or confidential information or intellectual property, or interference with our information technology systems, could result in business disruption, negative publicity, brand damage, violation of privacy laws, loss of customers, potential liability and competitive disadvantage all of which could have a material adverse effect on our business, financial condition or results of operations.

USE OF PROCEEDS

Unless we state otherwise in an accompanying prospectus supplement, we intend to use the net proceeds from the sale of the securities offered by us under this prospectus and any related prospectus supplement for general corporate purposes. These purposes may include capital expenditures, acquisitions and additions to working capital. When a particular offering of securities is made, the prospectus supplement relating to that offering will set forth our intended use of the net proceeds we receive from the sale of the securities. Pending the application of the net proceeds, we may invest the proceeds in short-term, interest-bearing instruments or other investment-grade securities.

DILUTION

With the exception of debt securities we may sell with no equity conversion feature and, therefore, no effect on dilution, we will set forth in a prospectus supplement the following information regarding any material dilution of the equity interests of investors purchasing securities sold by ClearSign in an offering under this prospectus:

DESCRIPTION OF THE SECURITIES THAT MAY BE OFFERED

Description of Debt Securities

The following description, together with the additional information we include in any applicable prospectus supplement, summarizes certain general terms and provisions of the debt securities that we may offer under this prospectus. When we offer to sell a particular series of debt securities, we will describe the specific terms of the series in a supplement to this prospectus. The supplement will also indicate to what extent the general terms and provisions described in this prospectus apply to a particular series of debt securities.

We may issue debt securities, either separately, or together with, or upon the conversion or exercise of or in exchange for, other securities described in this prospectus. Debt securities may be our senior, senior subordinated or subordinated obligations, issued in one or more series, and, unless otherwise specified in a supplement to this prospectus, the debt securities will be our direct, unsecured obligations.

The debt securities will be issued under an indenture between us and a trustee to be identified in the applicable prospectus supplement. We have summarized select portions of the indenture below. Please note, however, that the summary below is not complete. The form of the indenture has been filed as an exhibit to the registration statement of which this prospectus forms a part and you should read the indenture for provisions that may be important to you. Capitalized terms used in the summary below and not defined herein have the meanings specified in the form of the indenture.

General

The terms of each series of debt securities will be established by or pursuant to a resolution of our board of directors and set forth or determined in the manner provided in a resolution of our board of directors, in an officer’s certificate, or by a supplemental indenture. The particular terms of each series of debt securities will be described in a prospectus supplement relating to such series (including any pricing supplement or term sheet).

We can issue an unlimited amount of debt securities under the indenture that may be in one or more series with the same or various maturities, at par, at a premium, or at a discount. The prospectus supplement (including any pricing supplement or term sheet) relating to any series of debt securities being offered will set forth the aggregate principal amount and the other terms of the debt securities, including, if applicable:

We may issue debt securities that provide for an amount less than their stated principal amount to be due and payable upon declaration of acceleration of their maturity pursuant to the terms of the indenture. Information on the federal income tax considerations and other special considerations applicable to any of these debt securities will be provided in the applicable prospectus supplement.

If the purchase price of any of the debt securities is denominated in a foreign currency or currencies or a foreign currency unit or units, or if the principal of and any premium and interest on any series of debt securities is payable in a foreign currency or currencies or a foreign currency unit or units, then information on the restrictions, elections, general tax considerations, specific terms and other information with respect to that issue of debt securities and such foreign currency or currencies or foreign currency unit or units will be provided in the applicable prospectus supplement.

Transfer and Exchange

Each debt security will be represented by either one or more global securities registered in the name of The Depository Trust Company (which we refer to as “DTC”) or a nominee of DTC (which we refer to as a “book-entry debt security”), or a certificate issued in definitive registered form (which is referred to as a “certificated debt security”), as set forth in the applicable prospectus supplement. Except as set forth under the heading “Global Debt Securities and Book-Entry System” below, book-entry debt securities will not be issuable in certificated form.

Certificated Debt Securities. Holders may transfer or exchange certificated debt securities at any office we maintain for this purpose in accordance with the terms of the indenture. No service charge will be made for any transfer or exchange of certificated debt securities, but payment of a sum sufficient to cover any tax or other governmental charge payable in connection with a transfer or exchange may be required.

Holders may effect the transfer of certificated debt securities and the right to receive the principal of, or any premium or interest on, certificated debt securities only by surrendering the certificate representing those certificated debt securities and either reissuance by us or the trustee of the certificate to the new holder or the issuance by us or the trustee of a new certificate to the new holder.

Global Debt Securities and Book-Entry System. Each global debt security representing book-entry debt securities will be deposited with, or on behalf of, DTC, and registered in the name of DTC or a nominee of DTC.

Covenants

Any restrictive covenants applicable to any issue of debt securities will be set forth in the applicable prospectus supplement.

No Protection in the Event of a Change of Control

Unless stated otherwise in the applicable prospectus supplement, the debt securities will not contain any provisions that may afford holders of the debt securities protection in the event we have a change in control or in the event of a highly leveraged transaction (whether or not such transaction results in a change in control) that could adversely affect holders of debt securities.

Consolidation, Merger and Sale of Assets

We may not consolidate with or merge with or into, or convey, transfer or lease all or substantially all of our properties and assets to any person (a “successor person”) unless:

Notwithstanding the above, our subsidiaries may consolidate with, merge into, or transfer all or part of its properties to us.

Events of Default

“Event of Default” means with respect to any series of debt securities, any of the following:

No Event of Default with respect to a particular series of debt securities (except as to certain events of bankruptcy, insolvency or reorganization) necessarily constitutes an Event of Default with respect to any other series of debt securities. The occurrence of certain Events of Default or an acceleration under the indenture may constitute an event of default under certain other of our indebtedness or indebtedness of our subsidiaries outstanding from time to time.

So long as any of the securities are outstanding, we will provide the trustee written notice of any Default or Event of Default within 30 days of becoming aware of the occurrence of such Default or Event of Default.

If an Event of Default with respect to debt securities of any series at the time outstanding occurs and is continuing, then the trustee or the holders of not less than a majority in principal amount of the outstanding debt securities of that series may, by a notice in writing to us (and to the trustee if given by the holders), declare to be due and payable immediately the principal of (or, if the debt securities of that series are discount securities, that portion of the principal amount as may be specified in the terms of that series) and accrued and unpaid interest, if any, on all debt securities of that series. Such acceleration will not be effective until the earlier of (1) the acceleration of indebtedness under our senior secured credit facilities or (2) five business days after receipt by us of written notice of such acceleration, at which time the principal, premium, if any, interest and any other monetary obligations on all the then outstanding series of debt securities will become due and payable immediately. In the case of an Event of Default resulting from certain events of bankruptcy, insolvency or reorganization, the principal (or such specified amount) and accrued and unpaid interest, if any, on all outstanding debt securities or the applicable series will become and be immediately due and payable without any declaration or other act on the part of the trustee or any holder of outstanding debt securities. At any time after a declaration of acceleration with respect to debt securities of any series has been made, but before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in principal amount of the outstanding debt securities of that series may rescind and annul the acceleration if all Events of Default, other than the non-payment of accelerated principal and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the indenture. Please refer to the prospectus supplement relating to any series of debt securities that are discount securities for the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an Event of Default.

The indenture will provide that the trustee will be under no obligation to exercise any of its rights or powers under the indenture unless the trustee receives indemnity satisfactory to it against any cost, liability or expense which might be incurred by it in exercising such right of power. Subject to certain rights of the trustee, the holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to the debt securities of that series.

No holder of any debt security of any series will have any right to institute any proceeding, judicial or otherwise, with respect to the indenture or for the appointment of a receiver or trustee, or for any remedy under the indenture, unless:

Notwithstanding any other provision in the indenture, the holder of any debt security will have an absolute and unconditional right to receive payment of the principal of, premium and any interest on that debt security on or after the due dates expressed in that debt security and to institute suit for the enforcement of payment.

The indenture requires us, within 120 days after the end of our fiscal year, to furnish to the trustee a statement as to compliance with the indenture. If a Default or Event of Default occurs and is continuing with respect to the debt securities of any series and if it is known to a responsible officer of the trustee, the trustee shall mail to each holder of the debt securities of that series notice of a Default or Event of Default within 90 days after it occurs. The indenture provides that the trustee may withhold notice to the holders of debt securities of any series of any Default or Event of Default (except in payment on any debt securities of that series) with respect to debt securities of that series if the trustee determines in good faith that withholding notice is in the interest of the holders of those debt securities.

Modification and Waiver

We and the trustee may modify, amend or supplement the indenture or the debt securities of any series without the consent of any holder of any debt security:

We may also modify and amend the indenture with the consent of the holders of at least a majority in principal amount of the outstanding debt securities of each series affected by the modifications or amendments. We may not make any modification or amendment without the consent of the holders of each affected debt security then outstanding if that amendment will:

Except for certain specified provisions, the holders of at least a majority in principal amount of the outstanding debt securities of any series may, on behalf of the holders of all debt securities of that series, waive compliance by us with provisions of the indenture. The holders of a majority in principal amount of the outstanding debt securities of any series may, on behalf of the holders of all the debt securities of such series, waive any past default under the indenture with respect to that series and its consequences, except a default in the payment of the principal of or any interest on any debt security of that series; provided, however, that the holders of a majority in principal amount of the outstanding debt securities of any series may rescind an acceleration and its consequences, including any related payment default that resulted from the acceleration.

Defeasance of Debt Securities and Certain Covenants in Certain Circumstances

Legal Defeasance. The indenture provides that, unless otherwise provided by the terms of the applicable series of debt securities, we may be discharged from any and all obligations in respect of the debt securities of any series (subject to certain exceptions). We will be so discharged upon the deposit with the trustee, in trust, of money and/or U.S. government obligations or, in the case of debt securities denominated in a single currency other than U.S. dollars, government obligations of the government that issued or caused to be issued such currency, that, through the payment of interest and principal in accordance with their terms, will provide money in an amount sufficient in the opinion of a nationally recognized firm of independent public accountants or investment bank to pay and discharge each installment of principal, premium and interest on and any mandatory sinking fund payments in respect of the debt securities of that series on the stated maturity of those payments in accordance with the terms of the indenture and those debt securities.

This discharge may occur only if, among other things, we have delivered to the trustee an opinion of counsel stating that we have received from, or there has been published by, the United States Internal Revenue Service a ruling or, since the date of execution of the indenture, there has been a change in the applicable United States federal income tax law, in either case to the effect that, and based thereon such opinion shall confirm that, the holders of the debt securities of that series will not recognize income, gain or loss for United States federal income tax purposes as a result of the deposit, defeasance and discharge and will be subject to United States federal income tax on the same amounts and in the same manner and at the same times as would have been the case if the deposit, defeasance and discharge had not occurred.

Defeasance of Certain Covenants. The indenture provides that, unless otherwise provided by the terms of the applicable series of debt securities, upon compliance with certain conditions:

The conditions include:

Covenant Defeasance and Events of Default. In the event we exercise our option to effect covenant defeasance with respect to any series of debt securities and the debt securities of that series are declared due and payable because of the occurrence of any Event of Default, the amount of money and/or U.S. government obligations or foreign government obligations on deposit with the trustee will be sufficient to pay amounts due on the debt securities of that series at the time of their stated maturity but may not be sufficient to pay amounts due on the debt securities of that series at the time of the acceleration resulting from the Event of Default. However, we shall remain liable for those payments.

No Personal Liability of Directors, Officers, Employees or Stockholders

None of our past, present or future directors, officers, employees or stockholders, as such, will have any liability for any of our obligations under the debt securities or the indenture or for any claim based on, or in respect or by reason of, such obligations or their creation. By accepting a debt security, each holder waives and releases all such liability. This waiver and release is part of the consideration for the issue of the debt securities. However, this waiver and release may not be effective to waive liabilities under U.S. federal securities laws, and it is the view of the SEC that such a waiver is against public policy.

Governing Law

The indenture and the debt securities will be governed by, and construed in accordance with, the laws of the State of New York without regard to conflict of law principles that would result in the application of any law other than the law of the State of New York.

Description of Common Stock

The following summary of the rights of our common stock is not complete and is subject to and qualified in its entirety by reference to our articles of incorporation and bylaws, copies of which are included as exhibits to our registration statement on Form S-3, of which this prospectus forms a part. See “Where You Can Find More Information.”

We have 64,500,000 shares of capital stock authorized under our articles of incorporation, consisting of 62,500,000 shares of common stock and 2,000,000 shares of preferred stock.

As of June 25, 2019, we had 29,090,232 shares of common stock issued and outstanding. Our authorized but unissued shares of common stock are available for issuance without further action by our shareholders, unless such action is required by applicable law or the rules of The Nasdaq Stock Market or any other stock exchange or automated quotation system on which our securities may become listed or traded. If the approval of our shareholders is not so required, our board of directors may determine not to seek shareholder approval.

Holders of our common stock are entitled to such dividends as may be declared by our board of directors out of funds legally available for such purpose, subject to any preferential dividend rights of any then outstanding preferred stock. The shares of common stock are neither redeemable nor convertible. Holders of common stock have no preemptive or subscription rights to purchase any of our securities.

Each holder of our common stock is entitled to one vote for each such share outstanding in the holder’s name. No holder of common stock is entitled to cumulate votes in voting for directors.

In the event of our liquidation, dissolution or winding up, the holders of our common stock are entitled to receive pro rata our assets which are legally available for distribution, after payments of all debts and other liabilities and subject to the prior rights of any holders of preferred stock then outstanding. All of the outstanding shares of our common stock are fully paid and non-assessable. The shares of common stock offered by this prospectus will also be fully paid and non-assessable.

Our common stock is listed on the Nasdaq Capital Market under the symbol “CLIR”. On June 25, 2019, the last sale price of our common stock was $1.0947 per share. The transfer agent and registrar for our common stock is VStock Transfer, LLC. Its address is18 Lafayette Place, Woodmere, New York 11598, and its telephone number is (212) 828-8436.

Anti-Takeover Effects of Certain Provisions of Washington Law and Our Charter Documents

The following is a summary of certain provisions of Washington law, our articles of incorporation and our bylaws. This summary does not purport to be complete and is qualified in its entirety by reference to the corporate law of Washington and our articles of incorporation and bylaws.

Effect of Washington Anti-Takeover Statute. We are subject to Chapter 23B.19 of the Revised Code of Washington, an anti-takeover law (the “Anti-Takeover Statute”). In general, the Anti-Takeover Statute prohibits a target corporation from entering into a significant business transaction with an acquiring person for a period of five years following the acquiring person’s share acquisition unless

The Anti-Takeover Statute generally defines an “acquiring person” as a person or group of persons, other than the target corporation or a subsidiary of the target corporation, who is the beneficial owner of voting shares entitled to cast votes comprising 10% or more of the voting power of the target corporation; provided, however, that the term “acquiring person” does not include a person who (a) beneficially owned voting shares entitled to cast votes comprising 10% or more of the voting power of the target corporation on March 23, 1988; (b) acquired its voting shares of the target corporation solely by gift, inheritance, or in a transaction in which no consideration is exchanged; (c) equals or exceeds the 10% threshold as a result of action taken solely by the target corporation, such as redemption of shares, unless that person, by his own action, acquires additional shares of the target corporation; (d) beneficially owned voting shares entitled to cast votes comprising 10% or more of the voting power of the target corporation prior to the time the target corporation had a class of voting shares registered with the SEC pursuant to section 12 or 15 of the Securities Exchange Act; or (e) beneficially owned voting shares entitled to cast votes comprising 10% or more of the voting power of the target corporation prior to the time the target corporation amended its articles of incorporation to provide that the corporation shall be subject to the provisions of this chapter.

The Anti-Takeover Statute defines a “significant business transaction” as:

Finally, the Anti-Takeover Statute defines a “target corporation” as:

(i) The corporation has a class of voting shares registered with the SEC pursuant to Section 12 or 15 of the Securities Exchange Act; or

(ii) The corporation’s articles of incorporation have been amended to provide that such a corporation shall be subject to the provisions of this chapter, if the corporation did not have a class of voting shares registered with the SEC pursuant to section 12 or 15 of the Securities Exchange Act on the effective date of that amendment; and

(i) The corporation has a class of voting shares registered with the SEC pursuant to section 12 or 15 of the Securities Exchange Act;

(ii) The corporation’s principal executive office is located in the state;

(iii) The corporation has: (A) more than 10% of its shareholders of record resident in the state; or (B) more than 10% of its shares owned of record by state residents; or (C) 1,000 or more shareholders of record resident in the state;

(iv) A majority of the corporation’s employees, together with those of its subsidiaries, are residents of the state or the corporation, together with its subsidiaries, employs more than one thousand residents of the state; and

(v) A majority of the corporation’s tangible assets, together with those of its subsidiaries, measured by market value, are located in the state or the corporation, together with its subsidiaries, has more than fifty million dollars’ worth of tangible assets located in the state.

Our Charter Documents. Our charter documents include provisions that may have the effect of discouraging, delaying or preventing a change in control or an unsolicited acquisition proposal that a shareholder might consider favorable, including a proposal that might result in the payment of a premium over the market price for the shares held by our shareholders. Certain of these provisions are summarized in the following paragraphs.

Effects of authorized but unissued common stock and blank check preferred stock.One of the effects of the existence of authorized but unissued common stock and undesignated preferred stock may be to enable our board of directors to make more difficult or to discourage an attempt to obtain control of our Company by means of a merger, tender offer, proxy contest or otherwise, and thereby to protect the continuity of management. If, in the due exercise of its fiduciary obligations, the board of directors were to determine that a takeover proposal was not in our best interest, such shares could be issued by the board of directors without shareholder approval in one or more transactions that might prevent or render more difficult or costly the completion of the takeover transaction by diluting the voting or other rights of the proposed acquirer or insurgent shareholder group, by putting a substantial voting block in institutional or other hands that might undertake to support the position of the incumbent board of directors, by effecting an acquisition that might complicate or preclude the takeover, or otherwise.

In addition, our articles of incorporation grant our board of directors broad power to establish the rights and preferences of authorized and unissued shares of preferred stock. The issuance of shares of preferred stock could decrease the amount of earnings and assets available for distribution to holders of shares of common stock. The issuance also may adversely affect the rights and powers, including voting rights, of those holders and may have the effect of delaying, deterring or preventing a change in control of our Company.

Cumulative Voting. Our articles of incorporation do not provide for cumulative voting in the election of directors and accordingly do not allow holders of less than a majority of the stock to elect some directors.

Vacancies.Our bylaws provide that any vacancy occurring on our board of directors may be filled by the shareholders, by the board of directors or, if the directors in office constitute less than a quorum, by the affirmative vote of a majority of the remaining directors.

Special Meeting of Shareholders. A special meeting of shareholders may only be called by the chairperson of the board of directors, the president or the board of directors or by holders of at least 20% of all the votes entitled to be cast on any issue proposed to be considered at the special meeting. 

Description of Preferred Stock

Our articles of incorporation permit us to issue up to 2,000,000 shares of preferred stock in one or more series and with rights and preferences that may be fixed or designated by our board of directors without any further action by our shareholders. We currently have no shares of preferred stock outstanding.

Subject to the limitations prescribed in our articles of incorporation and under Washington law, our articles of incorporation authorize the board of directors, from time to time by resolution and without further shareholder action, to provide for the issuance of shares of preferred stock, in one or more series, and to fix the designation, limitations, voting powers, preferences and relative rights of the shares, including the right to convert the shares into shares of our common stock, and to fix the qualifications, limitations and restrictions thereof.

Description of Warrants

We may issue warrants for the purchase of any of our securities, including the securities we are registering. As explained below, each warrant will entitle its holder to purchase the securities subject to the warrant at an exercise price set forth in, or to be determined as set forth in, the related prospectus supplement. Warrants may be issued separately or together with securities. The warrants will be issued pursuant to warrant agreements.

The particular terms of each issue of warrants and the warrant agreement relating to the warrants will be described in the applicable prospectus supplement, including, as applicable:

Holders of warrants will not be entitled, solely by virtue of being holders, to vote, to consent, to receive dividends, to receive notice as shareholders with respect to any meeting of shareholders for the election of directors or any other matter, or to exercise any rights whatsoever as a holder of the securities purchasable upon exercise of the warrants.

In the case of debt warrants, the prospectus supplement will contain, where appropriate, the following additional information:

Description of Units

We may, from time to time, issue units comprised of one or more of the other securities described in this prospectus in any combination. A prospectus supplement will describe the specific terms of the units offered under that prospectus supplement, and any special considerations applicable to investing in those units. You must read the applicable prospectus supplement and any applicable unit agreement for a full understanding of the specific terms of any units. We will incorporate by reference into the registration statement of which this prospectus is a part the form of unit agreement, including a form of unit certificate, if any, that describes the terms of the series of units we are offering before the issuance of the related series of units. While the terms we have summarized below will generally apply to any future units that we may offer under this prospectus, we will describe the particular terms of any series of units that we may offer in more detail in the applicable prospectus supplement and incorporated documents. The terms of any units offered under a prospectus supplement may differ from the terms described below.

We may issue units consisting of common stock, preferred stock, warrants, subscription rights, debt securities or any combination thereof. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time, or at any time before a specified date.

We will describe in the applicable prospectus supplement and any incorporated documents the terms of the series of units, including the following:

The provisions described in this section, as well as those described under “Description of Debt Securities,” “Description of Common Stock,” “Description of Preferred Stock,” “Description of Warrants” and “Description of Subscription Rights” will apply to each unit and, as applicable, to each security included in each unit.

We may issue units in such amounts and in such numerous distinct series as we determine.

Each unit agent will act solely as our agent under the applicable unit agreement and will not assume any obligation or relationship of agency or trust with any holder of any unit. A unit agent may act as our agent for more than one series of units. A unit agent will have no duty or responsibility in case of any default by us under the applicable unit agreement or unit, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a unit, without the consent of the related unit agent or the holder of any other unit, may enforce by appropriate legal action its rights as holder under any security included in the unit.

We, the unit agent, and any of their agents may treat the registered holder of any unit certificate as an absolute owner of the units evidenced by that certificate for any purposes and as the person entitled to exercise the rights attaching to the units so requested.

Description of Subscription Rights

We may issue subscription rights to purchase common stock, preferred stock, debt securities or other securities. These subscription rights may be issued independently or together with any other security offered hereby and may or may not be transferable by the shareholder receiving the subscription rights in such offering. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other purchasers pursuant to which the underwriters or other purchasers may be required to purchase any securities remaining unsubscribed for after such offering.

The applicable prospectus supplement will describe the specific terms of any offering of subscription rights for which this prospectus is being delivered, including the following:

The description in the applicable prospectus supplement of any subscription rights we offer will not necessarily be complete and will be qualified in its entirety by reference to the applicable subscription rights certificate, which will be filed with the SEC if we offer subscription rights.

PLAN OF DISTRIBUTION

We may offer and sell the securities in any one or more of the following ways:

In addition, we may enter into option, share lending or other types of transactions that require us to deliver securities to an underwriter, broker or dealer, who will then resell or transfer the securities under this prospectus. We may also enter into hedging transactions with respect to our securities. For example, we may:

We may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by or borrowed from us or others to settle those sales or to close out any related open borrowings of securities, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of securities. The third party in such sale transactions will be an underwriter and, if not identified in this prospectus, will be identified in the applicable prospectus supplement (or a post-effective amendment). In addition, we may otherwise loan or pledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus. Such financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

Each time we sell securities, we will provide a prospectus supplement that will name any underwriter, dealer or agent involved in the offer and sale of the securities. Any prospectus supplement will also set forth the terms of the offering, including:

If underwriters or dealers are used in the sale, the securities will be acquired by the underwriters or dealers for their own account. We may sell the securities from time to time in one or more transactions:

Such sales may be effected:

Any securities covered by this prospectus that qualify for sale pursuant to Rule 144 under the Securities Act may be sold under Rule 144 rather than pursuant to this prospectus.

The securities may be offered to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more of such firms. Unless otherwise set forth in the prospectus supplement, the obligations of underwriters or dealers to purchase the securities offered will be subject to certain conditions precedent and the underwriters or dealers will be obligated to purchase all the offered securities if any are purchased. Any public offering price and any discount or concession allowed or re-allowed or paid by underwriters or dealers to other dealers may be changed from time to time.

The securities may be sold directly by us or through agents as designated from time to time. Any agent involved in the offer or sale of the securities in respect of which this prospectus is delivered will be named, and any commissions payable to such agent will be set forth in, the prospectus supplement. Unless otherwise indicated in the prospectus supplement, any such agent will be acting on a best efforts basis for the period of its appointment.

Offers to purchase the securities offered by this prospectus may be solicited, and sales of the securities may be made by us directly to institutional investors or others, who may be deemed to be underwriters within the meaning of the Securities Act with respect to any resale of the securities. The terms of any offer made in this manner will be included in the prospectus supplement relating to the offer.

Some of the underwriters, dealers or agents used by us in any offering of securities under this prospectus may be customers of, engage in transactions with, and perform services for us or affiliates of ours in the ordinary course of business. Underwriters, dealers, agents and other persons may be entitled to indemnification against and contribution toward certain civil liabilities, including liabilities under the Securities Act, and to be reimbursed for certain expenses.

Subject to any restrictions relating to debt securities in bearer form, any securities initially sold outside the United States may be resold in the United States through underwriters, dealers or otherwise.

Any underwriters to which offered securities are sold by us for public offering and sale may make a market in such securities, but those underwriters will not be obligated to do so and may discontinue any market making at any time.

The anticipated date of delivery of the securities offered by this prospectus will be described in the applicable prospectus supplement relating to the offering.

Any broker-dealer participating in the distribution of the securities may be deemed to be an “underwriter” within the meaning of the Securities Act with respect to any securities such entity sells pursuant to this prospectus.

To comply with the securities laws of some states, if applicable, the securities may be sold in these jurisdictions only through registered or licensed brokers or dealers. In addition, in some states the securities may not be sold unless they have been registered or qualified for sale or an exemption from registration or qualification requirements is available and is complied with.

There can be no assurance that we will sell all or any of the securities offered by this prospectus.

LEGAL MATTERS

Mitchell Silberberg & Knupp LLP,Los Angeles, California, will pass upon the validity of the securities offered in this prospectus. Any underwriters will also be advised about the validity of the securities and other legal matters by their own counsel, which will be named in the prospectus supplement.

EXPERTS

Gumbiner Savett Inc., independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2018, as set forth in their report, which is incorporated by reference in the prospectus and elsewhere in this registration statement. Our consolidated financial statements are incorporated by reference in reliance on the report of Gumbiner Savett Inc., given on their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form S-3 under the Securities Act of 1933, as amended (“Securities Act”), with respect to the securities covered by this prospectus. This prospectus, which is a part of the registration statement, does not contain all of the information set forth in the registration statement or the exhibits and schedules filed therewith. For further information with respect to us and the securities covered by this prospectus, please see the registration statement and the exhibits filed with the registration statement. The SEC maintains an internet website that contains reports, proxy and information statements and other information regarding registrants that file electronically with the SEC. The address of the website is http://www.sec.gov.

We are subject to the information and periodic reporting requirements of the Exchange Act and, in accordance therewith, we file periodic reports, proxy statements and other information with the SEC. Such periodic reports, proxy statements and other information are available for inspection and copying at the website of the SEC referred to above. We maintain a website at http://www.clearsign.com. You may access our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed pursuant to Sections 13(a) or 15(d) of the Exchange Act with the SEC free of charge at our website as soon as reasonably practicable after such material is electronically filed with, or furnished to, the SEC. Our website and the information contained on that site, or connected to that site, are not incorporated into and are not a part of this prospectus.

INFORMATION INCORPORATED BY REFERENCE

The SEC and applicable law permits us to “incorporate by reference” into this prospectus information that we have or may in the future file with or furnish to the SEC. This means that we can disclose important information by referring you to those documents. You should read carefully the information incorporated herein by reference because it is an important part of this prospectus. We hereby incorporate by reference the following documents into this prospectus:

Additionally, all documents filed by us with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (other than any portions of filings that are furnished rather than filed pursuant to Items 2.02 and 7.01 of a Current Report on Form 8-K), after the date of this prospectus and before the termination or completion of this offering (including all such documents filed with the SEC after the date of the initial registration statement and prior to the effectiveness of the registration statement) shall be deemed to be incorporated by reference into this prospectus from the respective dates of filing of such documents. Any information that we subsequently file with the SEC that is incorporated by reference as described above will automatically update and supersede any previous information that is part of this prospectus.

Upon written or oral request, we will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge, a copy of any or all of the documents incorporated by reference, other than exhibits to those documents unless the exhibits are specifically incorporated by reference in the documents. Please send requests to ClearSign Combustion Corporation, 12870 Interurban Avenue South, Seattle, Washington 98168, Attn: Brian Fike, Telephone: (206) 673-4848.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

The following statement sets forth the expenses and costs expected to be incurred by ClearSign Combustion Corporation in connection with the distribution of its securities being registered in this registration statement. All amounts are estimates. 

*Estimate

Item 15. Indemnification of Officers and Directors.

The following summary is qualified in its entirety by reference to the complete text of any statutes referred to below and the amended articles of incorporation of ClearSign Combustion Corporation, a Washington corporation.

The Company’s articles of incorporation provide that, to the fullest extent permitted by Washington law, the Company’s directors will not be liable to the Company or its shareholders for monetary damages. This provision, however, does not eliminate or limit liability for acts or omissions that involve intentional misconduct or a knowing violation of law by a director, for conduct violating Revised Code of Washington section 23B.08.310 (approval of an unlawful distribution) or for any transaction from which the director will personally receive a benefit in money, property, or services to which the director is not legally entitled. Pursuant to section 23B.08.5223B.08.520 of the Revised Code of Washington, because the Company’s articles of incorporation do not limit the obligation, the Company must indemnify a director who was wholly successful, on the merits or otherwise, in the defense of any proceeding to which the director was a party because of being a director against reasonable expenses incurred by the director in connection with the proceeding.

The Company’s bylaws further provide that each person who was, is or is threatened to be made a party to, or is otherwise involved in any threatened, pending or completed action, suit, claim or proceeding, whether civil, criminal, administrative or investigative and whether formal or informal, by reason of the fact that he or she is or was a director or officer of the Company or was serving at the Company’s request as a director, officer, partner, trustee, employee or agent of another entity, shall be indemnified and held harmless against all losses, claims, damages, liabilities and expenses actually and reasonably incurred or suffered in connection with the proceeding. This indemnification right continues even after the individual has ceased to be a director or officer or to serve at the Company’s request as a director, officer, partner, trustee, employee or agent of another entity. However, if the person indemnified initiates the proceeding, he or she shall be entitled to indemnification only if the proceeding was authorized or ratified by the Company’s board of directors. No indemnification will be provided for acts or omissions finally adjudged to be intentional misconduct or a knowing violation of law, for conduct finally adjudged to be in violation of Revised Code of Washington section 23B.08.310, for any transaction with respect to which it was finally adjudged that the indemnitee personally received a benefit in money, property or services to which the indemnitee was not legally entitled or if the Company is otherwise prohibited by applicable law from paying indemnification. The Company must advance expenses to an indemnitee for an indemnification obligation so long as the Company receives an undertaking by or on behalf of the indemnitee to repay all amounts so advanced if it is determined by a final judicial decision from which there is no further right to appeal that the indemnitee is not entitled to be indemnified.

Under our Director and Officer Insurance Policy, our directors and officers are providedThe Company maintains liability insurance coverage of $5 million subject to retention. The policy has a one year term with annual renewal possible. The policy can be terminatedfor the activities undertaken by the insured if there is a merger or acquisition which includes a changeofficers and directors in ownership of 50% of the voting shares. Upon such an occurrence the insurer may elect to cancel the policy. We may elect to then obtain “run off” insurance for a period of between one and six years at a cost of between 125% and 225% of the initial policy premium. The policy is a claim made policy. It covers only those claims made during the policy term. If an act giving rise to a claim occurs during the policy term, but the claim is not reported within 60 days of the termination or expiration policy, the claim will not be covered.their capacities as such.

We haveThe Company has entered into, and will enter into in the future, indemnification agreements with the individuals who serve as our officers and directors.directors (the “indemnified party”). Pursuant to these agreements, wethe Company will indemnify officers and directorsan indemnified party who areis made partiesa party to, or threatened to be made partiesparty to, any proceeding by reason of the fact that they arethe indemnified party is or were officerswas an officer or directors,director, or areis or werewas serving at ourthe Company’s request as a director, officer, employee, or agent of another entity. The agreements require usindemnification agreement requires the Company to indemnify our officers and directorsthe indemnified party against all expenses, judgments, fines and penalties actually and reasonably incurred by themhim or her in connection with the defense or settlement of any such proceeding, subject to the terms and conditions of the agreements.

Insofaragreement, including adetermination that indemnification of a director indemnified party is permissible because the director has met the applicable Standard of Conduct, as indemnification for liabilities arising underdefined in the Securities Act may beagreement.If so requested by the indemnified party, the Company will advance (within 10 business days of such request) all Expenses, as defined in the agreement, to the indemnified party. If it is determined that the indemnified party is not permitted to directors, officers and controlling personsbe indemnified under applicable law, the Company will be entitled to be reimbursed by the indemnified party for all amounts theretofore paid. An indemnified party will not be entitled to indemnification pursuant to the indemnification agreement in connection with any proceeding initiated by indemnified party against the Company or any director or officer of the Company pursuant to the foregoing provisions, or otherwise,unless (i) the Company has been advised thatjoined in or the Board has consented to the initiation of the proceeding, (ii) the proceeding is one to enforce indemnification rights under the indemnification agreement, or (iii) the proceeding is instituted after a Change in Control, as defined in the opinion of the Securitiesagreement, and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Company of expenses incurred or paid by a director, officer or controlling person of the Company in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Company will, unless in the opinion ofindependent counsel has approved its counsel that the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.initiation.

Item 16. Exhibits.

a) Exhibits.   

*Filed herewith.

**Previously filed.

(1) Incorporated by reference from the registrant’s registration statement on Form S-1, as amended, file number 333-177946, originally filed with the Securities and Exchange Commission on November 14, 2011.

(2) Incorporated by reference from the registrant’s pre-effective amendment no. 2 on the registration statement on Form S-1 filed with the Securities and Exchange Commission on February 7, 2012.

(3) Incorporated by reference from the registrant’s definitive proxy statement on Schedule 14a filed with the Securities and Exchange Commission on April 4, 2019.

(4) Incorporated by reference from the registrant’s Current Report on Form 8-K filed with the Securities and Exchange Commission on June 12, 2019.

(5) Incorporated by reference from the registrant’s Annual Report on Form 10-K for the year ended December 31, 2014 filed with the Securities and Exchange Commission on February 26, 2015.

(6) To be filed, if necessary, after effectiveness of this registration statement by an amendment to the registration statement or incorporated by reference to a Current Report on Form 8-K filed in connection with an underwritten offering of the securities offered hereunder.

Item 17. Undertakings.

��

provided, however, that:

Paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

SIGNATURES

In accordance with the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and authorized this Amendment No. 1 to Registration Statementregistration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Seattle, State of Washington, on January 4, 2016.June 27, 2019.

SIGNATURES AND POWER OF ATTORNEY

Know All Men By These Presents, that each person whose signature appears below constitutes and appoints Colin James Deller and Brian G. Fike, and each of them singly, as his true and lawful attorney-in-fact and agent with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any or all amendments (including any pre-effective or post-effective amendments) to this registration statement or any related registration statement that is to be effective upon filing pursuant to Rule 462(b), and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection with the above premises, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent or his substitute or substitutes, may lawfully do or cause to be done by virtue thereof.

In accordance with the requirements of the Securities Act of 1933, as amended, this Registration Statementregistration statement was signed by the following persons in the capacities and on the dates stated.