
                                                                   Exhibit 10q

              SUPPLEMENTAL AGREEMENT TO BRIDGE LOAN AGREEMENT

     Supplemental Agreement dated as of July 10, 1999 ("this Agreement") to
Bridge Loan Agreement dated as of May 8, 1998 (the "Loan  Agreement") among
Clean Diesel  Technologies,  Inc., a Delaware  corporation (the "Company"),
the  Lenders  under the Loan  Agreement  and the Lenders who have agreed to
become parties hereto as set forth on the attached  signature  pages,  (all
such Lenders being referred to collectively herein as the "Lenders").


                                Article 1.0
                     Definitions; Terms and Conditions

1.1  Definitions;   Terms  and  Conditions:  Rights  and  Obligations.  The
definitions  and the terms and  conditions  set forth in the Loan Agreement
shall be  applicable  to this  Agreement  as if fully set forth herein and,
unless  expressly  set  forth  herein  to  the  contrary,  the  rights  and
obligations  of the  Company  and the  Lenders in this  Agreement  shall be
identical to those set forth in the Loan Agreement.


                                Article 2.0
                             Supplemental Loan

2.1  Additional  Loan;  Purpose.  The Loan  Agreement is hereby  amended to
provide that the original  principal  amount of the Loan of One Million Two
Hundred Fifty Thousand Dollars (U.S.  $1,250,000.00) shall be increased and
supplemented  by an  addition  to the  Loan of up to  Seven  Hundred  Fifty
Thousand Dollars  (U.S.$750,000.00) (the "Supplemental Amount") for a total
aggregate amount of Loan of Two Million Dollars (U.S.  $2,000,000.00)  (the
"Total Loan"). The purpose of the Supplemental  Amount shall be the same as
set forth in the Loan Agreement.

2.2 Supplemental Lending. The Lenders by their execution of signature pages
to this  Agreement  agree to lend to the Company and the Company  agrees to
borrow  the  amounts  set  forth on such  signature  pages  hereto  as each
Lender's respective  Commitment hereunder and the Company shall deliver and
the Lenders  shall  accept a Note in form  similar to Exhibit B of the Loan
Agreement evidencing the lending of each such Commitment.


                                Article 3.0
             Consents; Security Agreement and Security Interest

3.1 Consents.  The several Lenders under the Loan Agreement  consent to the
lending by the  Lenders  hereunder  of the  Supplemental  Amount and to the
participation  by the  Lenders  hereunder  in  the  benefits  of  the  Loan
Agreement and Security Agreement, as amend, for so long as the Loan and the
Total Loan shall be outstanding.

3.2 Amendment of Security Agreement:  Supplemental Financing Statement. The
Company  and the  Lenders  agree  that the  lien  created  by the  Security
Agreement,  as amended,  shall secure the Total Loan  actually  made for so
long as it shall be  outstanding  and the  Security  Agreement  be,  and it
hereby is amended,  to provide that the Loan as defined  therein shall be a
sum equal to the Total Loan actually made and that a supplemental financing
statement be filed to reflect such amendment.

3.3 Amendment of Conversion  Limit. The limit of conversion of the Notes to
Series A Convertible  Preferred  Stock,  par value $0.05 per share,  of the
Company  (the  "Series A Stock") set forth in ss.3.1 of the Loan  Agreement
be, and it hereby is amended, to read 4,000.

3.4  Waiver  of  Conversion.  The  Lenders  hereby  waive  their  right  to
voluntarily  convert  the Notes to Series A Stock  until the earlier of (1)
January  31, 1999 or (2)  completion  by the Company of a private or public
sale of equity securities,  including rights to acquire securities,  of the
Company  pursuant  to which the  Company  shall  receive or be  entitled to
receive, net of the expenses and fees, discounts and commissions of lenders
or  investors,  underwriters,  placement  agents and  brokers  or  finders,
proceeds of at least U.S. $1,750,000.00.

IN WITNESS  WHEREOF,  the parties  hereto  have  caused  this  Supplemental
Agreement  to be duly  executed  by their  representatives  thereunto  duly
authorized, all as of the date first above written.

CLEAN DIESEL TECHNOLOGIES, INC.


By:  /s/ James M. Valentine
     ----------------------
     (Vice) President


PLATINUM PLUS, INC.


By:  /s/ Charles W. Grinnell
     -----------------------
     (Vice) President





S G ASSOCIATES LIMITED
As Agent for the Remaining
Lenders under Loan Agreement


By:  -----------------------
     Managing Director


The undersigned by its representative thereunto duly authorized does hereby
execute and deliver this  Supplemental  Agreement dated as of July 10, 1998
to Bridge Loan Agreement  dated as of May 8, 1998 and designates the amount
set forth below as its Commitment under such Agreement.

Amount of Commitment:   $ 150,000 (one hundred and fifty thousand US dollars)

  (Name of Lender)      POSITIVE SECURITIES LIMITED
                        31 The Parade, St. Helier
                        Jersey JE2 3QQ, Channel Islands

By:
    ------------------------
    Authorized Agent
