Celanese AG

PERSONAL AND CONFIDENTIAL

February 3, 2004

Management Board

Gentlemen:

You have requested our opinion as to the fairness from a financial point of view to the holders, other than Kuwait Petroleum Corporation, which we understand owns 29.2% of the outstanding Celanese Shares (as defined below) and as to which we express no opinion, of the registered ordinary shares with no par value (auf den Namen lautende Stckaktien ohne Nennbetrag) (the Celanese Shares) of Celanese AG (the Company), a stock corporation (Aktiengesellschaft, AG) organized and existing under the laws of the Federal Republic of Germany, of the 32.50 per Share in cash, without interest, proposed to be paid to such holders by BCP Crystal Acquisition GmbH & Co. KG (the Bidder), an acquisition entity indirectly owned by funds advised by The Blackstone Group L.P. (The Blackstone Group L.P. and funds advised by them, together Blackstone) in the Tender Offer (as defined below). Pursuant to the voluntary public takeover offer (freiwilliges ffentliches bernahmeangebot) for all of the Celanese Shares published in the offer document of the Bidder on February 2, 2004 and filed with the United States Securities and Exchange Commission under Schedule TO, the Bidder will pay upon successful completion 32.50 per Share in cash, without interest, for each Share accepted (the Tender Offer).

Goldman, Sachs & Co. oHG and its affiliates (Goldman Sachs), as part of their investment banking business, are continually engaged in performing financial analyses and valuations with respect to businesses and their securities in connection with mergers and acquisitions, negotiated underwritings, competitive biddings, secondary distributions of listed and unlisted securities and private placements as well as for estate, corporate and other purposes. We have acted as financial advisor to the Company in connection with, and have participated in certain of the negotiations leading to, the Tender Offer. We expect to receive fees for our services in connection with the Tender Offer, all of which fees are contingent upon consummation of the Tender Offer, and the Company has agreed to indemnify us against certain liabilities arising out of our engagement. In addition, we have provided, and are currently providing, certain investment banking and other services to the Company from time to time, including, among others, having acted as underwriter in two municipal bond offerings for CNA Holdings Inc., an indirect wholly owned subsidiary of Celanese AG, in April 2002 and currently acting as U.S. commercial paper dealer for Celanese Americas Corp. In addition, Kendrick R. Wilson III, a Managing Director of Goldman, Sachs & Co., is a member of the Supervisory Board of the Company. Goldman Sachs also has provided from time to time, and is currently providing, certain investment banking services to Blackstone, including, among others, having acted as financial advisor to a consortium of entities including Blackstone in connection with the consortiums acquisition of Houghton Mifflin Inc. in December 2002 and having participated in certain related acquisition financings; having acted as


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February 5, 2004

The Supervisory Board

Members of the Supervisory Board:

You have requested our opinion as to the fairness, from a financial point of view, to the holders of ordinary shares with no par value (the Company Common Stock) of Celanese AG (the Company) of the consideration to be received by such holders in the tender offer for all of the outstanding registered shares of Company Common Stock at a price of Euro 32.50 per share in cash (the Offer) by BCP Crystal Acquisition GmbH & Co. KG (the Acquiror), which is controlled by a group of investment funds advised by the Blackstone Group (Blackstone). The Offer is being made pursuant to the Offer Document, dated as of February 2, 2004 (the Offer Document). In a letter to shareholders dated December 23, 2003, the Management Board (Vorstand) of the Company announced its support for the Offer, subject to review of the formal tender offer documents.

In arriving at our opinion, we have (i) reviewed the Offer Document; (ii) reviewed certain publicly available business and financial information concerning the Company and the industries in which it operates; (iii) compared the proposed financial terms of the Offer with the publicly available financial terms of certain transactions involving companies we deemed relevant and the consideration received for such companies; (iv) compared the financial and operating performance of the Company with publicly available information concerning certain other companies we deemed relevant and reviewed the current and historical market prices of the Company Common Stock and certain publicly traded securities of such other companies; (v) reviewed certain internal financial analyses and forecasts prepared by the management of the Company relating to its business; and (vi) performed such other financial studies and analyses and considered such other information as we deemed appropriate for the purposes of this opinion.


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