THIS  SECURED  DEBENTURE,  AND  THE  SECURITIES  INTO  WHICH  IT IS  CONVERTIBLE
(COLLECTIVELY,  THE  "SECURITIES"),  HAVE NOT BEEN  REGISTERED  WITH THE  UNITED
STATES  SECURITIES AND EXCHANGE  COMMISSION OR THE SECURITIES  COMMISSION OF ANY
STATE.  THE  SECURITIES  ARE  BEING  OFFERED  PURSUANT  TO A  SAFE  HARBOR  FROM
REGISTRATION UNDER REGULATION D PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "ACT").  THE SECURITIES ARE  "RESTRICTED" AND MAY NOT BE OFFERED OR
SOLD UNLESS THE SECURITIES ARE REGISTERED UNDER THE ACT,  PURSUANT TO REGULATION
D OR PURSUANT TO AVAILABLE EXEMPTIONS FROM THE REGISTRATION  REQUIREMENTS OF THE
ACT AND THE  COMPANY  WILL BE  PROVIDED  WITH  OPINION  OF COUNSEL OR OTHER SUCH
INFORMATION  AS IT MAY  REASONABLY  REQUIRE TO CONFIRM THAT SUCH  EXEMPTIONS ARE
AVAILABLE. FURTHER HEDGING TRANSACTIONS INVOLVING THE SECURITIES MAY NOT BE MADE
EXCEPT IN COMPLIANCE WITH THE ACT.


                                SECURED DEBENTURE

                             TECH LABORATORIES INC.

                        5% SECURED CONVERTIBLE DEBENTURE

                                  MAY 28, 2004

No.  ___                                                           US$250,000.00

      This Secured  Debenture (the  "Debenture") is issued by Tech  Laboratories
Inc., a New Jersey corporation (the "Company"), to  ____________________________
(together with its permitted  successors and assigns,  the "Holder") pursuant to
exemptions from registration under the Securities Act of 1933, as amended.

                                   ARTICLE I.

      SECTION 1.01 PRINCIPAL AND INTEREST.  For value received,  on May 28, 2004
(the "Closing  Date"),  the Company  hereby  promises to pay to the order of the
Holder on May ___,  2007 in lawful money of the United  States of America and in
immediately available funds the principal sum of Two Hundred Fifty Thousand U.S.
DOLLARS  (US$250,000),  together with  interest on the unpaid  principal of this
Debenture at the rate of five percent (5%) per year  (computed on the basis of a
365-day year and the actual days elapsed) from the date of this Debenture  until
paid.  At the  Company's  option,  the entire  principal  amount and all accrued
interest  shall be  either  (a)  paid to the  Holder  on the  third  (3rd)  year
anniversary  from the date hereof or (b)  converted in  accordance  with Section
1.02 herein provided,  however, that in no event shall the Holder be entitled to
convert this  Debenture for a number of shares of Common Stock in excess of that
number of shares of Common Stock which,  upon giving effect to such  conversion,





would cause the aggregate number of shares of Common Stock beneficially owned by
the Holder and its affiliates to exceed 4.99% of the  outstanding  shares of the
Common Stock following such conversion.

      SECTION 1.02 OPTIONAL CONVERSION.  The Holder is entitled,  at its option,
to convert,  and sell on the same day, at any time and from time to time,  until
payment in full of this  Debenture,  all or any part of the principal  amount of
the Debenture,  plus accrued interest,  into shares (the "Conversion Shares") of
the Company's  common stock,  no par value per share  ("Common  Stock"),  at the
price per share (the  "Conversion  Price")  equal to the lesser of (a) an amount
equal to one  hundred  twenty  percent  (120%) of the  closing  bid price of the
Common Stock as listed on a Principal Market (as defined  herein),  as quoted by
Bloomberg L.P. (the "Closing Bid Price") as of the date hereof, or (b) an amount
equal to eighty  percent (80%) of the lowest  closing bid price of the Company's
Common Stock, as quoted by Bloomberg, LP (the "Closing Bid Price"), for the five
(5) trading days immediately  preceding the Conversion Date (as defined herein).
Subparagraphs  (a) and (b) above are  individually  referred to as a "Conversion
Price". As used herein,  "Principal Market" shall mean The National  Association
of Securities Dealers Inc.'s  Over-The-Counter  Bulletin Board,  Nasdaq SmallCap
Market,  or  American  Stock  Exchange.  If the Common  Stock is not traded on a
Principal  Market,  the Closing Bid Price shall mean,  the reported  Closing Bid
Price  for the  Common  Stock,  as  furnished  by the  National  Association  of
Securities  Dealers,  Inc., for the applicable periods. No fraction of shares or
scrip  representing  fractions of shares will be issued on  conversion,  but the
number of shares  issuable  shall be  rounded to the  nearest  whole  share.  To
convert this Debenture,  the Holder hereof shall deliver written notice thereof,
substantially  in the form of Exhibit "A" to this  Debenture,  with  appropriate
insertions (the "Conversion Notice"), to the Company at its address as set forth
herein.  The date upon which the conversion  shall be effective (the "Conversion
Date") shall be deemed to be the date set forth in the Conversion Notice.

      SECTION 1.03  RESERVATION  OF COMMON STOCK.  The Company shall reserve and
keep available out of its authorized but unissued shares of Common Stock, solely
for the purpose of effecting the  conversion of this  Debenture,  such number of
shares of Common Stock as shall from time to time be  sufficient  to effect such
conversion, based upon the Conversion Price. If at any time the Company does not
have a sufficient number of Conversion Shares authorized and available, then the
Company shall call and hold a special meeting of its  stockholders  within sixty
(60)  days of that  time  for the sole  purpose  of  increasing  the  number  of
authorized shares of Common Stock.

      SECTION 1.04 RIGHT OF REDEMPTION. The Company at its option shall have the
right to redeem,  with three (3)  business  days  advance  written  notice  (the
"Redemption Notice"), a portion or all outstanding  convertible  debenture.  The
redemption  price  shall be one  hundred  twenty  percent  (120%) of the  amount
redeemed plus accrued interest.

      In the event the Company exercises a redemption of either all or a portion
the Convertible Debenture,  the Holder shall receive a warrant to purchase fifty
thousand  (50,000)  shares of the  Company's  Common Stock for every One Hundred
Thousand U.S.  Dollars  (US$100,000)  redeemed,  pro rata (the  "Warrant").  The
Warrant shall be exercisable on a "cash basis" and have an exercise price of one
hundred and twenty  percent  (120%) of the  Closing  Bid Price of the  Company's


                                       2



Common Stock on the Closing Date. The Warrant shall have "piggy-back" and demand
registration rights and shall survive for two (2) years from the Closing Date.

      SECTION 1.05 REGISTRATION RIGHTS. The Company is obligated to register the
resale of the  Conversion  Shares under the  Securities Act of 1933, as amended,
pursuant to the terms of a Registration  Rights  Agreement,  between the Company
and  the  Holder  of even  date  herewith  (the  "Investor  Registration  Rights
Agreement").

      SECTION 1.06  INTEREST  PAYMENTS.  The interest so payable will be paid at
the time of maturity or conversion to the person in whose name this Debenture is
registered.  At the time such  interest  is  payable,  the  Holder,  in its sole
discretion,  may elect to receive  the  interest  in cash (via wire  transfer or
certified  funds) or in the form of Common  Stock.  In the event of default,  as
described in Article III Section 3.01  hereunder,  the Holder may elect that the
interest be paid in cash (via wire  transfer or certified  funds) or in the form
of Common Stock. If paid in the form of Common Stock,  the amount of stock to be
issued  will be  calculated  as  follows:  the value of the  stock  shall be the
Closing Bid Price on: (i) the date the  interest  payment is due; or (ii) if the
interest  payment is not made when due, the date the interest payment is made. A
number of shares of Common  Stock with a value  equal to the amount of  interest
due shall be issued.  No  fractional  shares will be issued;  therefore,  in the
event  that the value of the  Common  Stock  per share  does not equal the total
interest due, the Company will pay the balance in cash.

      SECTION 1.07 PAYING AGENT AND REGISTRAR.  Initially,  the Company will act
as paying  agent and  registrar.  The  Company  may  change  any  paying  agent,
registrar,  or  Company-registrar  by giving  the  Holder not less than ten (10)
business  days' written  notice of its election to do so,  specifying  the name,
address, telephone number and facsimile number of the paying agent or registrar.
The Company may act in any such capacity.

      SECTION 1.08 SECURED NATURE OF DEBENTURE. This Debenture is secured by all
of the  assets  and  property  of the  Company  as set forth on Exhibit A to the
Security Agreement dated the date hereof between the Company and the Holder (the
"Security Agreement"). As set forth in the Security Agreement, Holder's security
interest shall  terminate upon the occurrence of an Expiration  Event as defined
in the Security Agreement.

                                   ARTICLE II.

      SECTION 2.01  AMENDMENTS  AND WAIVER OF DEFAULT.  The Debenture may not be
amended.  Notwithstanding  the above,  without the  consent of the  Holder,  the
Debenture may be amended to cure any ambiguity,  defect or inconsistency,  or to
provide for assumption of the Company obligations to the Holder.

                                  ARTICLE III.

      SECTION 3.01 EVENTS OF DEFAULT. An Event of Default is defined as follows:
(a) failure by the Company to pay amounts due hereunder within fifteen (15) days
of the date of maturity of this Debenture;  (b) failure by the Company to comply
with the terms of the Irrevocable  Transfer Agent  Instructions  attached to the
Securities  Purchase  Agreement;  (c) failure by the Company's transfer agent to
issue freely  tradeable  Common Stock to the Holder  within five (5) days of the
Company's receipt of the attached Notice of Conversion from Holder;  (d) failure
by the  Company  for ten (10) days after  notice to it to comply with any of its


                                       3



other agreements in the Debenture; (e) events of bankruptcy or insolvency; (f) a
breach by the Company of its obligations under the Securities Purchase Agreement
or the Investor  Registration Rights Agreement which is not cured by the Company
within  ten  (10)  days  after  receipt  of  written  notice  thereof.  Upon the
occurrence  of an Event of  Default,  the Holder  may,  in its sole  discretion,
accelerate  full repayment of all debentures  outstanding  and accrued  interest
thereon or may,  notwithstanding  any  limitations  contained in this  Debenture
and/or the  Securities  Purchase  Agreement  dated the date  hereof  between the
Company  and  Cornell  Capital   Partners,   L.P.  (the   "Securities   Purchase
Agreement"),  convert all debentures  outstanding and accrued  interest  thereon
into shares of Common Stock pursuant to Section 1.02 herein.

      SECTION 3.02 FAILURE TO ISSUE  UNRESTRICTED  COMMON STOCK. As indicated in
Article III Section 3.01, a breach by the Company of its  obligations  under the
Investor  Registration  Rights  Agreement  shall be deemed an Event of  Default,
which if not cured within ten (10) days,  shall entitle the Holder to accelerate
full repayment of all debentures  outstanding and accrued  interest  thereon or,
notwithstanding   any  limitations   contained  in  this  Debenture  and/or  the
Securities Purchase Agreement, to convert all debentures outstanding and accrued
interest  thereon into shares of Common  Stock  pursuant to Section 1.02 herein.
The Company  acknowledges  that  failure to honor a Notice of  Conversion  shall
cause irreparable harm to the Holder.

                                  ARTICLE IV.

      SECTION 4.01 RIGHTS AND TERMS OF CONVERSION.  This Debenture,  in whole or
in part, may be converted at any time following the Closing Date, into shares of
Common  Stock at a price equal to the  Conversion  Price as described in Section
1.02 above.

      SECTION 4.02 RE-ISSUANCE OF DEBENTURE. When the Holder elects to convert a
part of the  Debenture,  then the Company  shall  reissue a new Debenture in the
same form as this Debenture to reflect the new principal amount.

      SECTION 4.03  TERMINATION  OF  CONVERSION  RIGHTS.  The Holder's  right to
convert the Debenture  into the Common Stock in accordance  with  paragraph 4.01
shall  terminate on the date that is the third (3rd) year  anniversary  from the
date hereof and this Debenture shall be automatically  converted on that date in
accordance  with  the  formula  set  forth  in  Section  4.01  hereof,  and  the
appropriate shares of Common Stock and amount of interest shall be issued to the
Holder.

                                   ARTICLE V.

      SECTION  5.01  ANTI-DILUTION.  In the event that the Company  shall at any
time subdivide the  outstanding  shares of Common Stock,  or shall issue a stock
dividend  on the  outstanding  Common  Stock,  the  Conversion  Price in  effect
immediately  prior to such subdivision or the issuance of such dividend shall be
proportionately  decreased,  and in the event that the Company shall at any time
combine the outstanding  shares of Common Stock,  the Conversion Price in effect
immediately  prior  to such  combination  shall  be  proportionately  increased,
effective at the close of business on the date of such subdivision,  dividend or
combination as the case may be.


                                       4



SECTION  5.02  CONSENT  OF  HOLDER  TO SELL  CAPITAL  STOCK  OR  GRANT  SECURITY
INTERESTS.  Except for the Standby Equity Distribution  Agreement dated the date
hereof between the Company and Cornell Capital  Partners,  LP, so long as any of
the principal of or interest on this Debenture  remains unpaid and  unconverted,
the Company shall not,  without the prior  consent of the Holder,  issue or sell
(i)  any  Common  Stock  or  Preferred  Stock  without  consideration  or  for a
consideration  per share less than its fair market value determined  immediately
prior to its issuance, (ii) issue or sell any Preferred Stock, warrant,  option,
right,  contract,  call,  or other  security or  instrument  granting the holder
thereof  the  right to  acquire  Common  Stock  without  consideration  or for a
consideration  per  share  less than  such  Common  Stock's  fair  market  value
determined  immediately  prior to its  issuance,  (iii) enter into any  security
instrument  granting the holder a security  interest in any of the assets of the
Company, or (iv) file any registration statement on Form S-8.

                                  ARTICLE VI.

SECTION 6.01  NOTICE.  Notices  regarding  this  Debenture  shall be sent to the
parties at the following  addresses,  unless a party notifies the other parties,
in writing, of a change of address:

If to the Company, to:             Tech Laboratories Inc.
                                   955 Belmont Avenue
                                   North Haledon, NJ 07508
                                   Attention: Bernard Ciongoli, President
                                   Telephone: (973) 427-5333
                                   Facsimile: (973) 427-5444

With a copy to:                    Kirkpatrick & Lockhart LLP
                                   201 South Biscayne Boulevard - Suite 2000
                                   Miami, FL  33131-2399
                                   Attention: Clayton E. Parker, Esq.
                                   Telephone: (305) 539-3300
                                   Facsimile: (305) 358-7095

If to the Holder:                  Cornell Capital Partners, LP
                                   101 Hudson Street, Suite 3606
                                   Jersey City, NJ 07303
                                   Telephone: (201) 985-8300
                                   Facsimile: (201) 985-8266

With a copy to:                    Butler Gonzalez LLP
                                   1416 Morris Avenue, Suite 207
                                   Union, NJ 07083
                                   Attention: David Gonzalez, Esq.
                                   Telephone: (908) 810-8588
                                   Facsimile: (908) 810-0973


                                       5



      SECTION 6.02  GOVERNING  LAW.  This  Debenture  shall be deemed to be made
under and shall be  construed  in  accordance  with the laws of the State of New
Jersey without giving effect to the principals of conflict of laws thereof. Each
of the parties consents to the  jurisdiction of the U.S.  District Court sitting
in the  District of the State of New Jersey or the state  courts of the State of
New Jersey sitting in Hudson County,  New Jersey in connection  with any dispute
arising under this Debenture and hereby waives,  to the maximum extent permitted
by law, any objection,  including any objection based on forum non conveniens to
the bringing of any such proceeding in such jurisdictions.

      SECTION 6.03 SEVERABILITY. The invalidity of any of the provisions of this
Debenture shall not invalidate or otherwise  affect any of the other  provisions
of this Debenture, which shall remain in full force and effect.

      SECTION 6.04 ENTIRE  AGREEMENT AND AMENDMENTS.  This Debenture  represents
the entire  agreement  between  the parties  hereto with  respect to the subject
matter  hereof  and there are no  representations,  warranties  or  commitments,
except as set forth herein.  This Debenture may be amended only by an instrument
in writing executed by the parties hereto.

      SECTION  6.05  COUNTERPARTS.  This  Debenture  may be executed in multiple
counterparts,  each of which  shall be an  original,  but all of which  shall be
deemed to constitute on instrument.

      IN  WITNESS  WHEREOF,  with the  intent to be legally  bound  hereby,  the
Company as executed this Debenture as of the date first written above.

                                           TECH LABORATORIES INC.

                                           By:    /s/Bernard Ciongoli
                                               ---------------------------------
                                           Name:  Bernard Ciongoli
                                           Title: President


                                       6



                                   EXHIBIT "A"

                              NOTICE OF CONVERSION

        (TO BE EXECUTED BY THE HOLDER IN ORDER TO CONVERT THE DEBENTURE)

TO:

         The  undersigned  hereby  irrevocably  elects  to  convert  US$  of the
principal  amount of the above  Debenture  into  Shares of Common  Stock of Tech
Laboratories  Inc.,  according  to  the  conditions  stated  therein,  as of the
Conversion Date written below.

CONVERSION DATE:
                                        ----------------------------------------
APPLICABLE CONVERSION PRICE:
                                        ----------------------------------------
SIGNATURE:
                                        ----------------------------------------
NAME:
                                        ----------------------------------------
ADDRESS:
                                        ----------------------------------------
AMOUNT TO BE CONVERTED:  US$
                                        ----------------------------------------
AMOUNT OF DEBENTURE UNCONVERTED: US$
                                        ----------------------------------------
CONVERSION PRICE PER SHARE: US$
                                        ----------------------------------------
NUMBER OF SHARES OF COMMON
STOCK TO BE ISSUED:
                                        ----------------------------------------
PLEASE ISSUE THE SHARES OF COMMON STOCK
IN THE FOLLOWING NAME AND TO THE
FOLLOWING ADDRESS:
                                        ----------------------------------------
ISSUE TO:
                                        ----------------------------------------
AUTHORIZED SIGNATURE:
                                        ----------------------------------------
NAME:
                                        ----------------------------------------
TITLE:
                                        ----------------------------------------
PHONE NUMBER:
                                        ----------------------------------------
BROKER DTC PARTICIPANT CODE:
ACCOUNT NUMBER:
                                        ----------------------------------------



                                      A-1