Re: Initial Public Offering

As of October 13, 2006

Alyst Acquisition Corp.

Jesup & Lamont Securities Corporation

650 Fifth Avenue

New York, New York 10019

Gentlemen:

Ira Hollenberg IRA (“Stockholder”), a stockholder of Alyst Acquisition Corp. (“Company”), in consideration of Jesup & Lamont Securities Corporation (“J&LSC”) entering into a letter of intent (“Letter of Intent”) to underwrite an initial public offering of the securities of the Company (“IPO”) and embarking on the IPO process, hereby agrees as follows (certain capitalized terms used herein are defined in paragraph 12 hereof):

1.   If the Company solicits approval of his stockholders of a Business Combination, Stockholder will vote all Insider Shares owned by it in accordance with the majority of the votes cast by the holders of the IPO Shares.

2.   Stockholder hereby waives any and all right, title, interest or claim of any kind in or to any distribution of the Trust Fund and any remaining net assets of the Company as a result of such liquidation with respect to his Insider Shares (“Claim”) and hereby waives any Claim it may have in the future as a result of, or arising out of, any contracts or agreements with the Company and will not seek recourse against the Trust Fund for any reason whatsoever.

3.   Stockholder acknowledges and agrees that the Company will not consummate any Business Combination which involves a company which is affiliated with any of the Insiders unless the Company obtains an opinion from an independent investment banking firm reasonably acceptable to J&LSC that the business combination is fair to the Company’s stockholders from a financial perspective.

4.   Neither Stockholder, any control person of Stockholder (“Control Person”), nor any affiliate of Stockholder (“Affiliate”) will be entitled to receive and will not accept any compensation for services rendered to the Company prior to or in connection with the consummation of the Business Combination; provided that Stockholder shall be entitled to reimbursement from the Company for his out-of-pocket expenses incurred in connection with seeking and consummating a Business Combination.

5.   Neither Stockholder, any Control Person, nor any Affiliate will be entitled to receive or accept a finder’s fee or any other compensation in the event the undersigned, any Control Person or any Affiliate of the undersigned originates a Business Combination.

6.   Stockholder will escrow all of his Insider Shares acquired prior to the IPO until one year after the consummation by the Company of a Busi