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                                                                      Exhibit 4h

[DYNAGEN, INC. LETTERHEAD]
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                                                                   June 25, 1998


Attn.: Stephen Hicks
Dominion Capital Fund
c/o Citco Asset Management
Bahamas Financial Center
Shirley & Charlotte Streets
Nassau, Bahamas

Dear Steve:

     This letter will confirm our agreement concerning when and under what 
conditions you will cause certain exercise rights under the Series H 
Convertible Preferred Stock. This Agreement is in consideration of your 
agreement to amend the terms of the $450,000 Limited Recourse Promissory Notes 
dated April 30, 1998 and May 13, 1998. These notes require DynaGen to repay the 
principal and interest amount out of the next private placement. You have 
agreed to convert these notes into equity at a 20% discount to the market. We 
will include these notes in the current S-3 being filed with the SEC.

     In consideration of the above agreement, we agree as follows:

      1.   The conversion price will be 80% of the average closing bid price
           over the 5 day period ending on the date of conversion.

      2.   The convertible preferred shall be convertible at the option of the
           holder into securities of the Company after a 90 day period after the
           date of initial issuance (the "Closing") at a conversion price (the
           "Conversion Price") equal to: 80% of the average closing bid price of
           the Company's Common Stock for the 5 business days prior to the
           business day on which the notice of conversion is transmitted by
           the holder(s).

           In the event that DynaGen completes the restructuring of its
           obligations to the former owners of Superior within 90 days, you will
           agree to convert after 120 days from the date of initial investment.


      3.   The Company, at its option, may redeem all or part of the investment
           at any time and without notice the Preferred Shares by paying in cash
           an amount equal to 125% of the face value of the Preferred Shares
           redeemed.

     
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DYNAGEN, INC.

                                             Stephen Hicks
                                             June 25, 1998
                                             Page 2



      4.   Under no circumstances will the aggregate conversion of the Preferred
           Shares exceed 19.9% of issued and outstanding shares of the Company.
           In the event that the conversion amount exceeds 19.9% of the shares
           outstanding, the Company will redeem the balance in cash based on the
           above redemption feature or obtain shareholder approval for the
           issuance of such shares or a combination of redemptions and
           shareholder approval.

      5.   Any unconverted shares of Preferred Stock will convert automatically
           or, if such conversion would exceed 19.9% of the outstanding shares
           of Common Stock, be redeemed at 125% of the full value of the
           Preferred Shares on the second anniversary of the Closing date.

      6.   The Company has agreed to file a registration statement under the
           Securities Act of 1933 with respect to the shares of Common Stock
           concurrently with the registration statement for the Company's 
           Series C and D Preferred Stock.

      If this is acceptable to you, please sign below and return a copy to us.
Thank you.

                                             Sincerely,

                                             /s/  Jay Wadekar

                                             Jay Wadekar
                                             Executive Vice President

JGW/cak

AGREED AND ACCEPTED BY:


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Signature


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Date