

                                                                    Exhibit 4h

           50,000 Shares of Series B Convertible Preferred Stock

                       CLEAN DIESEL TECHNOLOGIES, INC.

      Series B Convertible Preferred Stock (par value $0.05 per share)

                    Initially Offered Pursuant to Rights
                        Distributed to Shareholders

To Our Clients:

     Enclosed for your consideration are a Prospectus, dated ______ __,
1998 ("Prospectus"), and the Instructions as to Use of Rights Certificates
(the "Instructions") relating to the offering (the "Offering") of up to
50,000 shares of Series B Convertible Preferred Stock, par value $0.05 per
share (the "Series B Preferred Stock"), of Clean Diesel Technologies, Inc.
(the "Company"), at a price of $____ per share (the "Subscription Price")
pursuant to transferable rights ("Rights") distributed to holders of record
("Record Date Holders") of the Company's outstanding common shares, par
value $0.05 per share (the "Common Shares"), at the close of business on
________ ___, 1998 (the "Record Date"); provided, however, that Rights will
not be distributed to Record Date Holders who reside in jurisdictions where
the Rights have not been registered or where an exemption from registration
is not available, as more fully described in the Prospectus.

     As described in the accompanying Prospectus, you will receive one
Right for each 50 Common Shares carried by us in your account as of the
Record Date. Each Right will entitle you to subscribe for and purchase from
the Company one share of Series B Preferred Stock (the "Basic Subscription
Privilege") at the Subscription Price and each share of Series B Preferred
Stock will be immediately convertible, at no cost to the holder thereof,
into 33 Common Shares. If you fully exercise the Basic Subscription
Privilege you will also have the right (the "Oversubscription Privilege")
to subscribe, at the Subscription Price, for additional shares of Series B
Preferred Stock available after satisfaction of all subscriptions pursuant
to the Basic Subscription Privilege (the "Excess Shares"). If the number of
Excess Shares is not sufficient to satisfy all subscriptions pursuant to
the Oversubscription Privilege, the Excess Shares will be allocated pro
rata among those Rights Holders exercising the Oversubscription Privilege.

     Rights to exercise the Basic Subscription Privilege are transferable,
and Rights Holders that wish to sell their Rights may do so. There can be
no assurance, however, that a trading market in the Rights will develop
prior to their Expiration Date (as defined below). If a market develops for
the Rights, there is no assurance as to the price at which the Rights will
trade.

     The materials enclosed are being forwarded to you as the beneficial
owner of the Company's Common Shares carried by us in your account but not
registered in your name. Exercises and sales of Rights may only be made by
us as the registered holder of Rights and pursuant to your instructions.
Accordingly, we request instructions as to whether you wish us to elect to
subscribe for any Series B Preferred Stock or attempt to sell any Rights to
which you are entitled pursuant to the terms and subject to the conditions
set forth in the enclosed Prospectus and Instructions.

     Your instructions to us should be forwarded as promptly as possible to
permit us to exercise or sell Rights on your behalf in accordance with the
provisions of the Offering. The Offering will expire at 5:00 p.m. Eastern
Standard Time on_______ __, 1998, unless extended by the Company (the
"Expiration Date"). Once a Rights Holder has properly exercised the Basic
Subscription Privilege or the Oversubscription Privilege, such exercise may
not be revoked.

     If you wish to have us, on your behalf, exercise Rights to purchase
any Series B Preferred Stock to which you are entitled or attempt to sell
such Rights, please so instruct us by completing, executing and returning
to us the instruction form on the reverse side of this letter.

     THE RIGHTS  WILL ONLY BE GRANTED  TO,  AND MAY ONLY BE  EXERCISED  BY,
INVESTORS  RESIDING IN THE  FOLLOWING  JURISDICTIONS  WHERE THE  SECURITIES
OFFERED  HEREBY  HAVE  BEEN  REGISTERED  WITH  THE  APPROPRIATE  SECURITIES
REGULATORY  AUTHORITIES  OR WHERE AN EXEMPTION  FROM SUCH  REGISTRATION  IS
AVAILABLE:  OUTSIDE THE UNITED  STATES AND IN  COLORADO,  CONNECTICUT,  THE
DISTRICT OF COLUMBIA,  ILLINOIS,  INDIANA,  IOWA, KANSAS, MAINE,  MARYLAND,
MASSACHUSETTS,  NEVADA, NEW JERSEY, NEW YORK, NORTH CAROLINA, RHODE ISLAND,
VERMONT, VIRGINIA AND WASHINGTON. RIGHTS WILL NOT BE DISTRIBUTED TO HOLDERS
WHO RESIDE IN STATES  WHERE THE  SECURITIES  OFFERED  HEREBY  HAVE NOT BEEN
REGISTERED OR WHERE AN EXEMPTION FROM  REGISTRATION  IS NOT  AVAILABLE.  IN
ADDITION,  THE SERIES B PREFERRED STOCK MAY NOT BE TRANSFERRED TO RESIDENTS
OF  ANY  OF  THE  FOLLOWING  STATES:  ARIZONA,   FLORIDA,   GEORGIA,  OHIO,
PENNSYLVANIA OR TEXAS.

     IF WE DO NOT RECEIVE COMPLETE WRITTEN INSTRUCTIONS IN ACCORDANCE WITH
THE PROCEDURES OUTLINED IN THE PROSPECTUS, WE WILL NOT EXERCISE, TRANSFER
OR SELL YOUR RIGHTS, AND YOUR RIGHTS WILL EXPIRE VALUELESS.

     ANY QUESTIONS OR REQUESTS FOR ASSISTANCE CONCERNING THE OFFERING
SHOULD BE DIRECTED TO CHASEMELLON SHAREHOLDER SERVICES, [1-800-814-0304].

Very truly yours,
