Dated:  December 27, 2005

          NEITHER THIS DEBENTURE NOR THE SECURITIES INTO WHICH THIS DEBENTURE IS
          CONVERTIBLE  HAVE BEEN  REGISTERED  WITH THE  SECURITIES  AND EXCHANGE
          COMMISSION OR THE SECURITIES  COMMISSION OF ANY STATE IN RELIANCE UPON
          AN EXEMPTION  FROM  REGISTRATION  UNDER THE SECURITIES ACT OF 1933, AS
          AMENDED (THE "SECURITIES ACT"), AND,  ACCORDINGLY,  MAY NOT BE OFFERED
          OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE  REGISTRATION  STATEMENT UNDER
          THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A
          TRANSACTION  NOT  SUBJECT  TO, THE  REGISTRATION  REQUIREMENTS  OF THE
          SECURITIES  ACT AND IN ACCORDANCE  WITH  APPLICABLE  STATE  SECURITIES
          LAWS.

No. MEP-3                                                               $300,000

                             TECH LABORATORIES, INC.

                          Secured Convertible Debenture


                              Due December 27, 2006

     This Secured  Convertible  Debenture  (the  "Debenture")  is issued by TECH
LABORATORIES,  INC., a New Jersey  corporation  (the  "Obligor"),  to MONTGOMERY
EQUITY  PARTNERS,  LTD  (the  "Holder"),  pursuant  to that  certain  Securities
Purchase Agreement (the "Securities Purchase Agreement") of even date herewith.

     FOR VALUE RECEIVED, the Obligor hereby promises to pay to the Holder or its
successors  and assigns the  principal  sum of Three  Hundred  Thousand  Dollars
($300,000)  together with accrued but unpaid  interest on or before December 27,
2006 (the "Maturity Date") in accordance with the following terms:

     Interest. Interest shall accrue on the outstanding principal balance hereof
at an annual rate equal to fifteen  percent (15%).  Interest shall be calculated
on the basis of a 360-day  year and the actual  number of days  elapsed,  to the
extent  permitted by  applicable  law.  Interest  hereunder  will be paid to the
Holder or its assignee (as defined in Section 5) in whose name this Debenture is
registered on the records of the Obligor regarding registration and transfers of
Debentures (the "Debenture Register").

     Right of Redemption.  The Obligor at its option shall have the right,  with
three (3) business days advance  written notice (the  "Redemption  Notice"),  to
redeem a portion or all amounts  outstanding  under this Debenture  prior to the
Maturity Date provided that the Closing Bid Price of the of the Obligor's Common
Stock, as reported by Bloomberg,  LP, is less than the Fixed Conversion Price at
the time of the Redemption  Notice. The Obligor shall pay an amount equal to the
principal amount being redeemed plus a redemption premium ("Redemption Premium")
equal to twenty five percent (25%) of the principal  amount being redeemed,  and
accrued interest,  (collectively  referred to as the "Redemption  Amount").  The
Obligor  shall  deliver to the Holder the  Redemption  Amount on the third (3rd)



                                       1

business day after the Redemption Notice.

     Notwithstanding  the foregoing in the event that the Obligor has elected to
redeem a portion of the outstanding  principal amount and accrued interest under
this  Debenture  the Holder  shall be permitted to convert all or any portion of
this Debenture during such three business day period.

     Security  Agreements.  This Debenture is secured by an Amended and Restated
Security  Agreement  (the  "Security  Agreement")  of even date  herewith by and
between the Obligor and the Holder and an Amended and Restated Pledge and Escrow
Agreement (the "Pledge Agreement") of even date herewith among the Obligor,  the
Holder, the Pledgor and the Escrow Agent.

     Consent of Holder to Sell Capital  Stock or Grant  Security  Interests.  So
long as any of the principal amount or interest on this Debenture remains unpaid
and unconverted, the Obligor shall not, without the prior consent of the Holder,
(i) issue or sell any shares of Common Stock or preferred  stock with or without
consideration,  (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 with or without  consideration,  (iii) enter into
any security  instrument  granting the holder a security  interest in any of the
assets of the Obligor, or (iv) file any registration statements on Form S-8.

     Rights  of First  Refusal.  So long as any  portion  of this  Debenture  is
outstanding (including principal or accrued interest), if the Obligor intends to
raise  additional  capital  by the  issuance  or sale of  capital  stock  of the
Obligor,  including without  limitation shares of any class of Common Stock, any
class of preferred stock, options,  warrants or any other securities convertible
or exercisable into shares of Common Stock (whether the offering is conducted by
the Obligor, underwriter,  placement agent or any third party) the Obligor shall
be obligated to offer to the Holder such issuance or sale of capital  stock,  by
providing  in writing  the  principal  amount of capital it intends to raise and
outline of the material terms of such capital raise,  prior to the offering such
issuance  or sale of  capital  stock to any  third  parties  including,  but not
limited  to,  current  or  former  officers  or  directors,  current  or  former
shareholders and/or investors of the obligor,  underwriters,  brokers, agents or
other third  parties.  The Holder shall have ten (10) business days from receipt
of such notice of the sale or issuance of capital  stock to accept or reject all
or a portion of such capital raising offer.

     This Debenture is subject to the following additional provisions:

     Section 1. This Debenture is exchangeable for an equal aggregate  principal
amount of Debentures of different authorized denominations,  as requested by the
Holder  surrendering  the  same.  No  service  charge  will  be  made  for  such
registration of transfer or exchange.

     Section 2.        Events of Default.
     ---------         -----------------

     (a) An "Event  of  Default",  wherever  used  herein,  means any one of the
following  events  (whatever  the reason and  whether it shall be  voluntary  or



                                       2

involuntary or effected by operation of law or pursuant to any judgment,  decree
or order of any court, or any order, rule or regulation of any administrative or
governmental body):

          (i) Any default in the  payment of the  principal  of,  interest on or
     other  charges in respect of this  Debenture,  or the Amended and  Restated
     Convertible  Debenture of even date  herewith  issued by the Obligor to the
     Holder,  free of any  claim of  subordination,  as and when the same  shall
     become due and payable  (whether on a Conversion  Date or the Maturity Date
     or by acceleration or otherwise);

          (ii) The Obligor shall fail to observe or perform any other  covenant,
     agreement  or  warranty  contained  in, or  otherwise  commit any breach or
     default of any  provision  of this  Debenture  (except as may be covered by
     Section 2(a)(i) hereof) or any Transaction  Document (as defined in Section
     5) which is not cured with in the time prescribed;

          (iii) The Obligor or any subsidiary of the Obligor shall commence,  or
     there  shall be  commenced  against the  Obligor or any  subsidiary  of the
     Obligor  under  any  applicable  bankruptcy  or  insolvency  laws as now or
     hereafter  in  effect  or any  successor  thereto,  or the  Obligor  or any
     subsidiary  of  the  Obligor  commences  any  other  proceeding  under  any
     reorganization,   arrangement,  adjustment  of  debt,  relief  of  debtors,
     dissolution,  insolvency or liquidation or similar law of any  jurisdiction
     whether  now  or  hereafter  in  effect  relating  to  the  Obligor  or any
     subsidiary of the Obligor or there is commenced  against the Obligor or any
     subsidiary  of  the  Obligor  any  such  bankruptcy,  insolvency  or  other
     proceeding  which  remains  undismissed  for a period  of 61  days;  or the
     Obligor or any  subsidiary  of the  Obligor  is  adjudicated  insolvent  or
     bankrupt;  or any order of relief or other order approving any such case or
     proceeding  is  entered;  or the Obligor or any  subsidiary  of the Obligor
     suffers  any  appointment  of any  custodian,  private  or court  appointed
     receiver or the like for it or any  substantial  part of its property which
     continues  undischarged or unstayed for a period of sixty one (61) days; or
     the Obligor or any subsidiary of the Obligor makes a general assignment for
     the benefit of creditors;  or the Obligor or any  subsidiary of the Obligor
     shall fail to pay,  or shall  state  that it is unable to pay,  or shall be
     unable to pay,  its debts  generally  as they become due; or the Obligor or
     any  subsidiary of the Obligor shall call a meeting of its creditors with a
     view to arranging a composition,  adjustment or restructuring of its debts;
     or the Obligor or any subsidiary of the Obligor shall by any act or failure
     to act expressly  indicate its consent to,  approval of or  acquiescence in
     any of the  foregoing;  or any  corporate  or other  action is taken by the
     Obligor or any  subsidiary  of the Obligor for the purpose of effecting any
     of the foregoing;

          (iv) The Obligor or any subsidiary of the Obligor shall default in any
     of its  obligations  under  any other  debenture  or any  mortgage,  credit
     agreement or other facility,  indenture  agreement,  factoring agreement or
     other instrument under which there may be issued,  or by which there may be
     secured or evidenced any indebtedness for borrowed money or money due under
     any long term  leasing  or  factoring  arrangement  of the  Obligor  or any
     subsidiary  of the Obligor in an amount  exceeding  $100,000,  whether such
     indebtedness  now exists or shall  hereafter  be created  and such  default
     shall  result  in such  indebtedness  becoming  or being  declared  due and
     payable  prior  to the date on which  it  would  otherwise  become  due and
     payable;

          (v) The Common  Stock  shall  cease to be quoted for trading or listed
     for  trading  on either  the  Nasdaq OTC  Bulletin  Board  ("OTC"),  Nasdaq



                                       3

     SmallCap  Market,  New York Stock Exchange,  American Stock Exchange or the
     Nasdaq National Market (each, a "Subsequent Market") and shall not again be
     quoted or listed for trading  thereon  within five (5) Trading Days of such
     delisting;

          (vi) The Obligor or any  subsidiary of the Obligor shall be a party to
     any Change of Control  Transaction  (as  defined in Section 5) without  the
     prior written consent of the Holder;

          (vii)  The  Obligor   shall  fail  to  file  the   Underlying   Shares
     Registration  Statement (as defined in Section 5) with the  Commission  (as
     defined in Section  5), or the  Underlying  Shares  Registration  Statement
     shall not have been  declared  effective  by the  Commission,  in each case
     within  the time  periods  set forth in the  Investor  Registration  Rights
     Agreement  ("Registration  Rights Agreement") of even date herewith between
     the Obligor and the Holder;

          (viii) If the  effectiveness  of the  Underlying  Shares  Registration
     Statement  lapses for any reason or the Holder  shall not be  permitted  to
     resell the  shares of Common  Stock  underlying  this  Debenture  under the
     Underlying  Shares  Registration  Statement,  in either case, for more than
     five (5)  consecutive  Trading Days or an  aggregate of eight  Trading Days
     (which need not be consecutive Trading Days);

          (ix) The  Obligor  shall fail for any reason to deliver  Common  Stock
     certificates  to a Holder  prior to the  fifth  (5th)  Trading  Day after a
     Conversion  Date  or the  Obligor  shall  provide  notice  to  the  Holder,
     including by way of public announcement,  at any time, of its intention not
     to comply with  requests for  conversions  of this  Debenture in accordance
     with the terms hereof;

          (x) The  Obligor  shall fail for any reason to deliver  the payment in
     cash pursuant to a Buy-In (as defined  herein)  within three (3) days after
     notice is claimed delivered hereunder;

     (b) During the time that any portion of this Debenture is  outstanding,  if
any Event of Default has occurred,  the full principal amount of this Debenture,
together with interest and other amounts owing in respect  thereof,  to the date
of  acceleration  shall become at the  Holder's  election,  immediately  due and
payable in cash,  provided  however,  the Holder may request  (but shall have no
obligation  to request)  payment of such amounts in Common Stock of the Obligor.
In addition to any other remedies,  the Holder shall have the right (but not the
obligation)  to convert this Debenture at any time after (x) an Event of Default
or (y) the Maturity Date at the Conversion Price then in-effect. The Holder need
not provide and the Obligor hereby waives any  presentment,  demand,  protest or
other notice of any kind, and the Holder may immediately and without  expiration
of any grace period enforce any and all of its rights and remedies hereunder and
all other remedies available to it under applicable law. Such declaration may be
rescinded and annulled by Holder at any time prior to payment hereunder. No such
rescission or annulment  shall affect any subsequent  Event of Default or impair
any right  consequent  thereon.  Upon an Event of Default,  notwithstanding  any
other provision of this Debenture or any Transaction Document,  the Holder shall
have no obligation to comply with or adhere to any  limitations,  if any, on the
conversion of this Debenture or the sale of the Underlying Shares.



                                       4

     Section 3.      Conversion.
     ---------       ----------

     (a) Conversion at Option of Holder.

          (i) This Debenture shall be convertible into shares of Common Stock at
     the option of the Holder,  in whole or in part at any time and from time to
     time,  after the Original  Issue Date (as defined in Section 5) (subject to
     the limitations on conversion set forth in Section 3(b) hereof). The number
     of shares of Common Stock issuable upon a conversion  hereunder  equals the
     quotient obtained by dividing (x) the outstanding  amount of this Debenture
     to be  converted  by (y)  the  Conversion  Price  (as  defined  in  Section
     3(c)(i)). The Obligor shall deliver Common Stock certificates to the Holder
     prior to the Fifth (5th) Trading Day after a Conversion Date.

          (ii) Notwithstanding  anything to the contrary contained herein, if on
     any  Conversion  Date: (1) the number of shares of Common Stock at the time
     authorized,  unissued and unreserved for all purposes,  or held as treasury
     stock, is insufficient to pay principal and interest hereunder in shares of
     Common  Stock;  (2) the Common Stock is not listed or quoted for trading on
     the OTC or on a  Subsequent  Market;  (3) the  Obligor has failed to timely
     satisfy its conversion;  or (4) the issuance of such shares of Common Stock
     would result in a violation  of Section  3(b),  then,  at the option of the
     Holder, the Obligor,  in lieu of delivering shares of Common Stock pursuant
     to Section  3(a)(i),  shall deliver,  within three (3) Trading Days of each
     applicable  Conversion  Date, an amount in cash equal to the product of the
     outstanding  principal amount to be converted plus any interest due therein
     divided by the Conversion  Price,  chosen by the Holder,  and multiplied by
     the highest  closing price of the stock from date of the conversion  notice
     till the date that such cash payment is made.

     Further, if the Obligor shall not have delivered any cash due in respect of
conversion  of this  Debenture  or as payment of  interest  thereon by the fifth
(5th) Trading Day after the  Conversion  Date,  the Holder may, by notice to the
Obligor, require the Obligor to issue shares of Common Stock pursuant to Section
3(c), except that for such purpose the Conversion Price applicable thereto shall
be the lesser of the Conversion  Price on the Conversion Date and the Conversion
Price on the date of such Holder demand.  Any such shares will be subject to the
provisions of this Section.

          (iii) The Holder shall effect conversions by delivering to the Obligor
     a completed  notice in the form attached hereto as Exhibit A (a "Conversion
     Notice").  The  date on  which a  Conversion  Notice  is  delivered  is the
     "Conversion  Date."  Unless the Holder is converting  the entire  principal
     amount  outstanding  under this  Debenture,  the Holder is not  required to
     physically  surrender  this  Debenture  to the  Obligor  in order to effect
     conversions.  Conversions  hereunder  shall have the effect of lowering the
     outstanding  principal amount of this Debenture plus all accrued and unpaid
     interest  thereon  in an amount  equal to the  applicable  conversion.  The
     Holder and the Obligor shall maintain  records showing the principal amount
     converted and the date of such conversions.  In the event of any dispute or
     discrepancy,   the  records  of  the  Holder  shall  be   controlling   and
     determinative in the absence of manifest error.

     (b) Certain Conversion Restrictions.



                                       5

          (i) A Holder may not  convert  this  Debenture  or  receive  shares of
     Common Stock as payment of interest hereunder to the extent such conversion
     or receipt of such interest  payment  would result in the Holder,  together
     with  any  affiliate  thereof,   beneficially   owning  (as  determined  in
     accordance with Section 13(d) of the Exchange Act and the rules promulgated
     thereunder) in excess of 4.9% of the then issued and outstanding  shares of
     Common Stock,  including shares issuable upon conversion of, and payment of
     interest on, this Debenture  held by such Holder after  application of this
     Section.  Since the Holder will not be  obligated  to report to the Obligor
     the  number  of  shares  of  Common  Stock  it may  hold  at the  time of a
     conversion  hereunder,  unless the  conversion at issue would result in the
     issuance  of  shares  of  Common  Stock  in  excess  of  4.9%  of the  then
     outstanding shares of Common Stock without regard to any other shares which
     may be beneficially owned by the Holder or an affiliate thereof, the Holder
     shall  have  the  authority  and   obligation  to  determine   whether  the
     restriction  contained in this Section will limit any particular conversion
     hereunder and to the extent that the Holder  determines that the limitation
     contained in this Section  applies,  the  determination of which portion of
     the  principal  amount  of  this  Debenture  is  convertible  shall  be the
     responsibility  and obligation of the Holder. If the Holder has delivered a
     Conversion  Notice for a principal  amount of this Debenture that,  without
     regard  to  any  other  shares  that  the  Holder  or  its  affiliates  may
     beneficially  own,  would result in the issuance in excess of the permitted
     amount  hereunder,  the  Obligor  shall  notify the Holder of this fact and
     shall honor the conversion for the maximum principal amount permitted to be
     converted on such Conversion Date in accordance with the periods  described
     in Section  3(a)(i)  and,  at the option of the Holder,  either  retain any
     principal  amount tendered for conversion in excess of the permitted amount
     hereunder for future  conversions or return such excess principal amount to
     the Holder.  The  provisions of this Section may be waived by a Holder (but
     only as to itself and not to any other  Holder)  upon not less than 65 days
     prior notice to the Obligor.  Other Holders shall be unaffected by any such
     waiver.

     (c) Conversion Price and Adjustments to Conversion Price.

          (i) The Holder shall be entitled to convert,  at its sole  option,  at
     any time a  portion  or all  amounts  of  principal  and  interest  due and
     outstanding  under this Debenture into shares of the Obligor's Common Stock
     at the lesser of (i) at a price equal to  $0.00525 ( the "Fixed  Conversion
     Price") or (ii) ninety percent (90%) of the lowest Closing Bid Price of the
     Common Stock during the ten (10) trading  days  immediately  preceding  the
     Conversion Date as quoted by Bloomberg, LP (the "Market Conversion Price").
     The Fixed Conversion Price and the Market Conversion Price are collectively
     referred to as the "Conversion Price." The Conversion Price may be adjusted
     pursuant to the other terms of this Debenture.

          (ii) If the Obligor,  at any time while this Debenture is outstanding,
     shall  (a)  pay a  stock  dividend  or  otherwise  make a  distribution  or
     distributions  on shares of its Common  Stock or any other equity or equity
     equivalent  securities  payable in shares of Common  Stock,  (b)  subdivide
     outstanding  shares of Common  Stock into a larger  number of  shares,  (c)
     combine  (including  by way of reverse stock split)  outstanding  shares of
     Common   Stock  into  a  smaller   number  of  shares,   or  (d)  issue  by
     reclassification  of shares of the Common Stock any shares of capital stock
     of the Obligor,  then the Fixed  Conversion  Price shall be multiplied by a
     fraction  of which the  numerator  shall be the  number of shares of Common
     Stock (excluding treasury shares, if any) outstanding before such event and
     of which the  denominator  shall be the  number  of shares of Common  Stock
     outstanding  after such event. Any adjustment made pursuant to this Section



                                       6

     shall  become  effective   immediately   after  the  record  date  for  the
     determination  of  stockholders   entitled  to  receive  such  dividend  or
     distribution  and shall become  effective  immediately  after the effective
     date in the case of a subdivision, combination or re-classification.

          (iii) If the Obligor, at any time while this Debenture is outstanding,
     shall issue rights, options or warrants to all holders of Common Stock (and
     not to the Holder)  entitling  them to subscribe for or purchase  shares of
     Common  Stock at a price per share  less than the Fixed  Conversion  Price,
     then the Fixed Conversion Price shall be multiplied by a fraction, of which
     the  denominator  shall  be  the  number  of  shares  of the  Common  Stock
     (excluding  treasury shares, if any) outstanding on the date of issuance of
     such rights or  warrants  (plus the number of  additional  shares of Common
     Stock offered for  subscription  or  purchase),  and of which the numerator
     shall be the  number of  shares of the  Common  Stock  (excluding  treasury
     shares,  if any)  outstanding  on the date of  issuance  of such  rights or
     warrants,  plus the number of shares which the aggregate  offering price of
     the  total  number  of  shares  so  offered  would  purchase  at the  Fixed
     Conversion  Price.  Such  adjustment  shall be made whenever such rights or
     warrants  are issued,  and shall  become  effective  immediately  after the
     record date for the determination of stockholders  entitled to receive such
     rights,  options or  warrants.  However,  upon the  expiration  of any such
     right,  option  or  warrant  to  purchase  shares of the  Common  Stock the
     issuance of which resulted in an adjustment in the Fixed  Conversion  Price
     pursuant to this Section, if any such right, option or warrant shall expire
     and  shall not have  been  exercised,  the  Fixed  Conversion  Price  shall
     immediately  upon such  expiration be recomputed and effective  immediately
     upon such  expiration  be  increased  to the price which it would have been
     (but reflecting any other  adjustments in the Fixed  Conversion  Price made
     pursuant  to the  provisions  of this  Section  after the  issuance of such
     rights or warrants) had the adjustment of the Fixed  Conversion  Price made
     upon the  issuance of such  rights,  options or  warrants  been made on the
     basis of offering for  subscription  or purchase only that number of shares
     of the Common Stock  actually  purchased  upon the exercise of such rights,
     options or warrants actually exercised.

          (iv) If the Obligor or any subsidiary thereof,  as applicable,  at any
     time while this  Debenture  is  outstanding,  shall issue  shares of Common
     Stock or rights,  warrants,  options or other  securities  or debt that are
     convertible  into or exchangeable for shares of Common Stock ("Common Stock
     Equivalents")  entitling any Person to acquire shares of Common Stock, at a
     price per share less than the Fixed  Conversion Price (if the holder of the
     Common  Stock or  Common  Stock  Equivalent  so  issued  shall at any time,
     whether by  operation  of purchase  price  adjustments,  reset  provisions,
     floating  conversion,  exercise or exchange prices or otherwise,  or due to
     warrants,  options or rights per share which is issued in  connection  with
     such issuance, be entitled to receive shares of Common Stock at a price per
     share which is less than the Fixed Conversion Price, such issuance shall be
     deemed to have occurred for less than the Fixed Conversion Price), then, at
     the sole option of the Holder, the Fixed Conversion Price shall be adjusted
     to mirror the conversion,  exchange or purchase price for such Common Stock
     or Common Stock  Equivalents  (including any reset  provisions  thereof) at
     issue.  Such adjustment  shall be made whenever such Common Stock or Common
     Stock  Equivalents  are  issued.  The  Obligor  shall  notify the Holder in
     writing,  no later than one (1) business day  following the issuance of any
     Common Stock or Common Stock Equivalent subject to this Section, indicating
     therein the  applicable  issuance  price,  or of  applicable  reset  price,
     exchange  price,  conversion  price and other pricing terms.  No adjustment
     under this Section  shall be made as a result of issuances and exercises of



                                       7

     options to purchase shares of Common Stock issued for compensatory purposes
     pursuant to any of the Obligor's stock option or stock purchase plans.

          (v) If the Obligor,  at any time while this Debenture is  outstanding,
     shall  distribute  to all  holders of Common  Stock (and not to the Holder)
     evidences of its  indebtedness or assets or rights or warrants to subscribe
     for or purchase any security,  then in each such case the Fixed  Conversion
     Price at which this  Debenture  shall  thereafter be  convertible  shall be
     determined by multiplying the Fixed Conversion Price in effect  immediately
     prior to the record date fixed for  determination of stockholders  entitled
     to receive such  distribution by a fraction of which the denominator  shall
     be the Closing Bid Price  determined as of the record date mentioned above,
     and of which the  numerator  shall be such Closing Bid Price on such record
     date less the then fair market  value at such record date of the portion of
     such assets or evidence of  indebtedness  so distributed  applicable to one
     outstanding  share  of the  Common  Stock  as  determined  by the  Board of
     Directors in good faith. In either case the adjustments  shall be described
     in a statement provided to the Holder of the portion of assets or evidences
     of indebtedness so distributed or such  subscription  rights  applicable to
     one share of Common Stock.  Such adjustment shall be made whenever any such
     distribution  is made and  shall  become  effective  immediately  after the
     record date mentioned above.

          (vi)  In case  of any  reclassification  of the  Common  Stock  or any
     compulsory  share exchange  pursuant to which the Common Stock is converted
     into other  securities,  cash or property,  the Holder shall have the right
     thereafter to, at its option,  (A) convert the then  outstanding  principal
     amount, together with all accrued but unpaid interest and any other amounts
     then owing  hereunder in respect of this Debenture into the shares of stock
     and other  securities,  cash and property  receivable  upon or deemed to be
     held by holders of the Common  Stock  following  such  reclassification  or
     share  exchange,  and the Holder of this  Debenture  shall be entitled upon
     such event to receive  such amount of  securities,  cash or property as the
     shares of the Common Stock of the Obligor  into which the then  outstanding
     principal  amount,  together  with all accrued but unpaid  interest and any
     other amounts then owing  hereunder in respect of this Debenture could have
     been converted immediately prior to such reclassification or share exchange
     would  have been  entitled,  or (B)  require  the  Obligor  to  prepay  the
     outstanding principal amount of this Debenture, plus all interest and other
     amounts due and payable thereon.  The entire prepayment price shall be paid
     in   cash.   This   provision   shall   similarly   apply   to   successive
     reclassifications or share exchanges.

          (vii) The Obligor shall at all times reserve and keep available out of
     its  authorized  Common  Stock the full  number  of shares of Common  Stock
     issuable upon conversion of all  outstanding  amounts under this Debenture;
     and within three (3) Business Days  following the receipt by the Obligor of
     a Holder's  notice that such minimum number of Underlying  Shares is not so
     reserved,  the Obligor shall promptly reserve a sufficient number of shares
     of Common Stock to comply with such requirement.

          (viii) All  calculations  under this  Section 3 shall be rounded up to
     the nearest $0.001 or whole share.



                                       8

          (ix) Whenever the Conversion  Price is adjusted  pursuant to Section 3
     hereof,  the Obligor  shall  promptly  mail to the Holder a notice  setting
     forth the Conversion  Price after such adjustment and setting forth a brief
     statement of the facts requiring such adjustment.

          (x) If (A)  the  Obligor  shall  declare  a  dividend  (or  any  other
     distribution)  on the Common Stock; (B) the Obligor shall declare a special
     nonrecurring  cash dividend on or a redemption of the Common Stock; (C) the
     Obligor  shall  authorize  the  granting to all holders of the Common Stock
     rights or warrants to subscribe for or purchase any shares of capital stock
     of any class or of any rights;  (D) the approval of any stockholders of the
     Obligor shall be required in connection  with any  reclassification  of the
     Common Stock, any  consolidation or merger to which the Obligor is a party,
     any sale or  transfer  of all or  substantially  all of the  assets  of the
     Obligor,  of any  compulsory  share  exchange  whereby the Common  Stock is
     converted into other securities, cash or property; or (E) the Obligor shall
     authorize the voluntary or involuntary dissolution,  liquidation or winding
     up of the affairs of the Obligor;  then,  in each case,  the Obligor  shall
     cause to be filed at each  office or agency  maintained  for the purpose of
     conversion of this Debenture, and shall cause to be mailed to the Holder at
     its last address as it shall appear upon the stock books of the Obligor, at
     least twenty (20) calendar days prior to the applicable record or effective
     date hereinafter specified, a notice stating (x) the date on which a record
     is to be taken for the purpose of such dividend, distribution,  redemption,
     rights or warrants, or if a record is not to be taken, the date as of which
     the holders of the Common Stock of record to be entitled to such  dividend,
     distributions,  redemption,  rights or warrants are to be determined or (y)
     the date on  which  such  reclassification,  consolidation,  merger,  sale,
     transfer or share  exchange is expected to become  effective or close,  and
     the date as of which it is  expected  that  holders of the Common  Stock of
     record  shall be entitled to exchange  their shares of the Common Stock for
     securities,  cash or other property deliverable upon such reclassification,
     consolidation, merger, sale, transfer or share exchange, provided, that the
     failure to mail such notice or any defect therein or in the mailing thereof
     shall not  affect the  validity  of the  corporate  action  required  to be
     specified in such notice.  The Holder is entitled to convert this Debenture
     during the 20-day calendar period commencing the date of such notice to the
     effective date of the event triggering such notice.

          (xi) In case of any (1) merger or  consolidation of the Obligor or any
     subsidiary of the Obligor with or into another  Person,  or (2) sale by the
     Obligor  or any  subsidiary  of the  Obligor of more than  one-half  of the
     assets of the Obligor in one or a series of related transactions,  a Holder
     shall have the right to (A)  exercise any rights under  Section  2(b),  (B)
     convert the aggregate  amount of this Debenture then  outstanding  into the
     shares of stock and other securities,  cash and property receivable upon or
     deemed  to be held by  holders  of  Common  Stock  following  such  merger,
     consolidation or sale, and such Holder shall be entitled upon such event or
     series of related  events to receive  such amount of  securities,  cash and
     property as the shares of Common Stock into which such aggregate  principal
     amount of this  Debenture  could have been converted  immediately  prior to
     such merger, consolidation or sales would have been entitled, or (C) in the
     case of a merger or consolidation, require the surviving entity to issue to
     the Holder a  convertible  Debenture  with a principal  amount equal to the
     aggregate principal amount of this Debenture then held by such Holder, plus
     all accrued and unpaid interest and other amounts owing thereon, which such
     newly issued  convertible  Debenture shall have terms identical  (including
     with respect to  conversion) to the terms of this  Debenture,  and shall be
     entitled  to all of the  rights  and  privileges  of  the  Holder  of  this
     Debenture  set forth  herein  and the  agreements  pursuant  to which  this



                                       9

     Debentures  were issued.  In the case of clause (C), the  conversion  price
     applicable  for the newly issued shares of convertible  preferred  stock or
     convertible  Debentures shall be based upon the amount of securities,  cash
     and  property  that  each  share of  Common  Stock  would  receive  in such
     transaction  and the Conversion  Price in effect  immediately  prior to the
     effectiveness or closing date for such  transaction.  The terms of any such
     merger, sale or consolidation shall include such terms so as to continue to
     give the Holder the right to receive the securities,  cash and property set
     forth in this Section upon any  conversion  or  redemption  following  such
     event. This provision shall similarly apply to successive such events.

     (d) Other Provisions.

          (i) The Obligor  covenants  that it will at all times reserve and keep
     available out of its authorized and unissued  shares of Common Stock solely
     for the purpose of issuance upon  conversion of this  Debenture and payment
     of  interest  on  this  Debenture,  each  as  herein  provided,  free  from
     preemptive rights or any other actual contingent purchase rights of persons
     other than the  Holder,  not less than such  number of shares of the Common
     Stock as shall (subject to any additional requirements of the Obligor as to
     reservation of such shares set forth in this Debenture) be issuable (taking
     into account the  adjustments  and  restrictions of Sections 2(b) and 3(c))
     upon the conversion of the outstanding  principal  amount of this Debenture
     and payment of interest hereunder. The Obligor covenants that all shares of
     Common  Stock that shall be so  issuable  shall,  upon  issue,  be duly and
     validly  authorized,  issued  and fully  paid,  nonassessable  and,  if the
     Underlying Shares Registration  Statement has been declared effective under
     the  Securities  Act,  registered  for public sale in accordance  with such
     Underlying Shares Registration Statement.

          (ii) Upon a conversion  hereunder the Obligor shall not be required to
     issue stock  certificates  representing  fractions  of shares of the Common
     Stock,  but may if otherwise  permitted,  make a cash payment in respect of
     any final  fraction of a share based on the Closing Bid Price at such time.
     If the Obligor elects not, or is unable,  to make such a cash payment,  the
     Holder  shall be entitled to  receive,  in lieu of the final  fraction of a
     share, one whole share of Common Stock.

          (iii) The issuance of  certificates  for shares of the Common Stock on
     conversion  of this  Debenture  shall be made without  charge to the Holder
     thereof for any  documentary  stamp or similar taxes that may be payable in
     respect of the issue or delivery  of such  certificate,  provided  that the
     Obligor shall not be required to pay any tax that may be payable in respect
     of any  transfer  involved  in  the  issuance  and  delivery  of  any  such
     certificate upon conversion in a name other than that of the Holder of such
     Debenture  so converted  and the Obligor  shall not be required to issue or
     deliver such certificates  unless or until the person or persons requesting
     the issuance  thereof shall have paid to the Obligor the amount of such tax
     or shall have  established to the satisfaction of the Obligor that such tax
     has been paid.

          (iv)  Nothing  herein  shall limit a Holder's  right to pursue  actual
     damages or declare an Event of Default pursuant to Section 2 herein for the
     Obligor 's failure to deliver  certificates  representing  shares of Common
     Stock upon conversion  within the period  specified  herein and such Holder
     shall have the right to pursue all  remedies  available  to it at law or in
     equity  including,  without  limitation,  a decree of specific  performance
     and/or  injunctive  relief, in each case without the need to post a bond or



                                       10

     provide other security.  The exercise of any such rights shall not prohibit
     the Holder from seeking to enforce  damages  pursuant to any other  Section
     hereof or under applicable law.

          (v) In addition to any other rights  available  to the Holder,  if the
     Obligor  fails to deliver to the Holder such  certificate  or  certificates
     pursuant  to  Section  3(a)(i)  by the fifth  (5th)  Trading  Day after the
     Conversion  Date,  and if after such  fifth  (5th)  Trading  Day the Holder
     purchases  (in an open market  transaction  or  otherwise)  Common Stock to
     deliver in satisfaction  of a sale by such Holder of the Underlying  Shares
     which the Holder  anticipated  receiving upon such conversion (a "Buy-In"),
     then the  Obligor  shall (A) pay in cash to the Holder (in  addition to any
     remedies available to or elected by the Holder) the amount by which (x) the
     Holder's total purchase price (including brokerage commissions, if any) for
     the Common Stock so purchased  exceeds (y) the product of (1) the aggregate
     number of shares of Common  Stock that such  Holder  anticipated  receiving
     from the  conversion  at issue  multiplied  by (2) the market  price of the
     Common  Stock  at the  time  of the  sale  giving  rise  to  such  purchase
     obligation and (B) at the option of the Holder,  either reissue a Debenture
     in the  principal  amount equal to the  principal  amount of the  attempted
     conversion  or deliver  to the Holder the number of shares of Common  Stock
     that  would have been  issued  had the  Obligor  timely  complied  with its
     delivery  requirements  under Section 3(a)(i).  For example,  if the Holder
     purchases  Common Stock having a total purchase price of $11,000 to cover a
     Buy-In with respect to an attempted  conversion of Debentures  with respect
     to  which  the  market  price  of the  Underlying  Shares  on the  date  of
     conversion  was a total of  $10,000  under  clause  (A) of the  immediately
     preceding sentence, the Obligor shall be required to pay the Holder $1,000.
     The Holder shall provide the Obligor written notice  indicating the amounts
     payable to the Holder in respect of the Buy-In.

          Section  4.  Notices.   Any  notices,   consents,   waivers  or  other
     communications  required or  permitted  to be given under the terms  hereof
     must be in  writing  and will be deemed to have  been  delivered:  (i) upon
     receipt,  when  delivered  personally;  (ii)  upon  receipt,  when  sent by
     facsimile  (provided   confirmation  of  transmission  is  mechanically  or
     electronically  generated and kept on file by the sending party);  or (iii)
     one (1) trading day after  deposit with a nationally  recognized  overnight
     delivery service,  in each case properly  addressed to the party to receive
     the same. The addresses and facsimile numbers for such communications shall
     be:


If to the Company, to:        Tech Laboratories, Inc.
                              c/o Anslow & Jaclin, LLP
                              195 Route 9 South, Suite 204
                              Manalapan, NJ 07726
                              Attention:        Gregg E. Jaclin
                              Telephone:        (973) 427-5333


If to the Holder:             Montgomery Equity Partners, Ltd
                              101 Hudson Street, Suite 3700
                              Jersey City, NJ 07303
                              Attention:        Mark Angelo
                              Telephone:        (201) 985-8300



                                       11

With a copy to:               David Gonzalez, Esq.
                              101 Hudson Street - Suite 3700
                              Jersey City, NJ 07302
                              Telephone:        (201) 985-8300
                              Facsimile:        (201) 985-8266


or at such other address and/or facsimile number and/or to the attention of such
other person as the  recipient  party has  specified by written  notice given to
each other  party three (3)  business  days prior to the  effectiveness  of such
change.  Written  confirmation  of receipt  (i) given by the  recipient  of such
notice,   consent,   waiver  or  other   communication,   (ii)  mechanically  or
electronically  generated by the sender's facsimile machine containing the time,
date,  recipient  facsimile  number  and an  image  of the  first  page  of such
transmission  or (iii) provided by a nationally  recognized  overnight  delivery
service, shall be rebuttable evidence of personal service,  receipt by facsimile
or receipt from a nationally recognized overnight delivery service in accordance
with clause (i), (ii) or (iii) above, respectively.

     Section 5. Definitions.  For the purposes hereof, the following terms shall
have the following meanings:

     "Business  Day"  means any day  except  Saturday,  Sunday and any day which
shall be a federal  legal holiday in the United States or a day on which banking
institutions  are  authorized or required by law or other  government  action to
close.

     "Change of Control  Transaction" means the occurrence of (a) an acquisition
after the date hereof by an  individual or legal entity or "group" (as described
in Rule  13d-5(b)(1)  promulgated  under the Exchange Act) of effective  control
(whether through legal or beneficial  ownership of capital stock of the Obligor,
by  contract or  otherwise)  of in excess of fifty  percent  (50%) of the voting
securities of the Obligor (except that the  acquisition of voting  securities by
the Holder  shall not  constitute a Change of Control  Transaction  for purposes
hereof), (b) a replacement at one time or over time of more than one-half of the
members of the board of  directors  of the  Obligor  which is not  approved by a
majority of those  individuals  who are members of the board of directors on the
date hereof (or by those  individuals who are serving as members of the board of
directors on any date whose nomination to the board of directors was approved by
a majority of the members of the board of directors  who are members on the date
hereof), (c) the merger, consolidation or sale of fifty percent (50%) or more of
the assets of the Obligor or any subsidiary of the Obligor in one or a series of
related  transactions  with or into another entity,  or (d) the execution by the
Obligor of an agreement to which the Obligor is a party or by which it is bound,
providing for any of the events set forth above in (a), (b) or (c).

     "Commission" means the Securities and Exchange Commission.
      ----------

     "Common Stock" means the common stock,  par value $0.01, of the Obligor and
stock of any other  class  into which such  shares may  hereafter  be changed or
reclassified.



                                       12

     "Conversion  Date"  shall  mean the date upon  which the  Holder  gives the
Obligor  notice of their  intention to effectuate a conversion of this Debenture
into shares of the Company's Common Stock as outlined herein.

     "Closing Bid Price" means the price per share in the last reported trade of
the Common  Stock on the OTC or on the  exchange  which the Common Stock is then
listed as quoted by Bloomberg, LP.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended.

     "Original  Issue  Date"  shall mean the date of the first  issuance of this
Debenture  regardless of the number of transfers and regardless of the number of
instruments, which may be issued to evidence such Debenture.

     "Person" means a corporation, an association, a partnership,  organization,
a business,  an individual,  a government or political  subdivision thereof or a
governmental agency.

     "Securities  Act" means the  Securities  Act of 1933,  as amended,  and the
rules and regulations promulgated thereunder.

     "Trading Day" means a day on which the shares of Common Stock are quoted on
the OTC or quoted or traded  on such  Subsequent  Market on which the  shares of
Common  Stock are then  quoted or listed;  provided,  that in the event that the
shares of Common  Stock are not listed or quoted,  then Trading Day shall mean a
Business Day.

     "Transaction  Documents"  means the  Securities  Purchase  Agreement or any
other agreement  delivered in connection with the Securities Purchase Agreement,
including,  without limitation,  the Amended and Restated Pledge Agreement,  the
Irrevocable  Transfer Agent Instructions,  and the Investor  Registration Rights
Agreement,  and the  Amended and  Restated  Convertible  Debenture  of even date
herewith.

     "Underlying  Shares"  means  the  shares  of  Common  Stock  issuable  upon
conversion of this  Debenture or as payment of interest in  accordance  with the
terms hereof.

     "Underlying Shares Registration  Statement" means a registration  statement
meeting  the  requirements  set  forth  in the  Registration  Rights  Agreement,
covering among other things the resale of the  Underlying  Shares and naming the
Holder as a "selling stockholder" thereunder.

     Section 6.  Except as  expressly  provided  herein,  no  provision  of this
Debenture  shall  alter or impair  the  obligations  of the  Obligor,  which are
absolute and unconditional,  to pay the principal of, interest and other charges
(if any) on, this  Debenture at the time,  place,  and rate,  and in the coin or
currency,  herein  prescribed.  This  Debenture  is a direct  obligation  of the
Obligor.  This  Debenture  ranks  pari passu  with all other  Debentures  now or
hereafter issued under the terms set forth herein.  As long as this Debenture is
outstanding,  the Obligor shall not and shall cause their  subsidiaries  not to,
without the consent of the Holder,  (i) amend its certificate of  incorporation,
bylaws or other  charter  documents so as to adversely  affect any rights of the
Holder;  (ii)  repay,  repurchase  or offer to repay,  repurchase  or  otherwise
acquire shares of its Common Stock or other equity  securities  other than as to
the Underlying  Shares to the extent permitted or required under the Transaction



                                       13

Documents;  or  (iii)  enter  into  any  agreement  with  respect  to any of the
foregoing.

     Section 7. This Debenture shall not entitle the Holder to any of the rights
of a stockholder  of the Obligor,  including  without  limitation,  the right to
vote, to receive dividends and other distributions, or to receive any notice of,
or to attend,  meetings of stockholders or any other proceedings of the Obligor,
unless and to the extent  converted  into shares of Common  Stock in  accordance
with the terms hereof.

     Section 8. If this Debenture is mutilated,  lost, stolen or destroyed,  the
Obligor shall  execute and deliver,  in exchange and  substitution  for and upon
cancellation of the mutilated Debenture,  or in lieu of or in substitution for a
lost, stolen or destroyed Debenture, a new Debenture for the principal amount of
this Debenture so mutilated,  lost, stolen or destroyed but only upon receipt of
evidence  of such  loss,  theft or  destruction  of such  Debenture,  and of the
ownership hereof, and indemnity,  if requested,  all reasonably  satisfactory to
the Obligor.

     Section 9. No  indebtedness  of the Obligor is senior to this  Debenture in
right of payment, whether with respect to interest,  damages or upon liquidation
or dissolution or otherwise.  Without the Holder's consent, the Obligor will not
and will not permit any of their subsidiaries to, directly or indirectly,  enter
into, create,  incur, assume or suffer to exist any indebtedness of any kind, on
or with respect to any of its property or assets now owned or hereafter acquired
or any  interest  therein or any income or profits  there from that is senior in
any respect to the obligations of the Obligor under this Debenture.

     Section 10. This Debenture shall be governed by and construed in accordance
with the laws of the State of New Jersey,  without giving effect to conflicts of
laws thereof.  Each of the parties  consents to the jurisdiction of the Superior
Courts of the State of New Jersey sitting in Hudson  County,  New Jersey and the
U.S. District Court for the District of New Jersey sitting in Newark, 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 11. If the Obligor fails to strictly  comply with the terms of this
Debenture,  then the Obligor shall  reimburse the Holder  promptly for all fees,
costs and expenses, including, without limitation,  attorneys' fees and expenses
incurred  by the  Holder  in any  action  in  connection  with  this  Debenture,
including, without limitation, those incurred: (i) during any workout, attempted
workout,  and/or in  connection  with the  rendering  of legal  advice as to the
Holder's rights, remedies and obligations, (ii) collecting any sums which become
due  to the  Holder,  (iii)  defending  or  prosecuting  any  proceeding  or any
counterclaim to any proceeding or appeal;  or (iv) the protection,  preservation
or enforcement of any rights or remedies of the Holder.

     Section 12. Any waiver by the Holder of a breach of any  provision  of this
Debenture  shall  not  operate  as or be  construed  to be a waiver of any other
breach  of such  provision  or of any  breach  of any  other  provision  of this
Debenture. The failure of the Holder to insist upon strict adherence to any term
of this Debenture on one or more  occasions  shall not be considered a waiver or



                                       14

deprive that party of the right  thereafter  to insist upon strict  adherence to
that term or any other term of this Debenture. Any waiver must be in writing.

     Section 13. If any  provision  of this  Debenture  is  invalid,  illegal or
unenforceable,  the balance of this Debenture shall remain in effect, and if any
provision is inapplicable to any person or circumstance,  it shall  nevertheless
remain applicable to all other persons and  circumstances.  If it shall be found
that any interest or other amount deemed  interest due  hereunder  shall violate
applicable laws governing  usury,  the applicable rate of interest due hereunder
shall  automatically be lowered to equal the maximum permitted rate of interest.
The Obligor  covenants  (to the extent that it may lawfully do so) that it shall
not at any time insist upon,  plead, or in any manner  whatsoever  claim or take
the benefit or advantage of, any stay, extension or usury law or other law which
would  prohibit  or forgive  the  Obligor  from paying all or any portion of the
principal of or interest on this  Debenture  as  contemplated  herein,  wherever
enacted,  now or at any time  hereafter  in  force,  or  which  may  affect  the
covenants or the performance of this  indenture,  and the Obligor (to the extent
it may lawfully do so) hereby  expressly waives all benefits or advantage of any
such law,  and  covenants  that it will not, by resort to any such law,  hinder,
delay or impeded the  execution of any power herein  granted to the Holder,  but
will  suffer and permit  the  execution  of every such as though no such law has
been enacted.

     Section 14. Whenever any payment or other obligation hereunder shall be due
on a day other  than a  Business  Day,  such  payment  shall be made on the next
succeeding Business Day.

     Section 15. THE PARTIES HEREBY  KNOWINGLY,  VOLUNTARILY  AND  INTENTIONALLY
WAIVE  THE  RIGHT  ANY OF THEM  MAY HAVE TO A TRIAL  BY JURY IN  RESPECT  OF ANY
LITIGATION  BASED  HEREON OR ARISING OUT OF,  UNDER OR IN  CONNECTION  WITH THIS
AGREEMENT  OR ANY  TRANSACTION  DOCUMENT  OR ANY  COURSE OF  CONDUCT,  COURSE OF
DEALING,  STATEMENTS  (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF ANY PARTY.  THIS
PROVISION  IS  A  MATERIAL  INDUCEMENT  FOR  THE  PARTIES'  ACCEPTANCE  OF  THIS
AGREEMENT.

                   [REMAINDER OF PAGE INTENTIONLLY LEFT BLANK]



                                       15

     IN WITNESS  WHEREOF,  the  Obligor  has  caused  this  Secured  Convertible
Debenture to be duly  executed by a duly  authorized  officer as of the date set
forth above.

                                   TECH LABORATORIES, INC.

                                   By:/s/ Donna Silverman
                                      ---------------------
                                   Name:  Donna Silverman
                                   Title: Chief Executive Officer



                                       16

                                   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 $ 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:                   $-------------------------------------
Amount of Debenture unconverted:          $-------------------------------------
Conversion Price per share:               $-------------------------------------
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:                           --------------------------------------