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                                                                    Exhibit 10.1


                              DATED AUGUST 19, 2005




                                     Between



                      CELANESE EUROPE HOLDING GMBH & CO. KG

                                as the Purchaser




                                       and




                              PAULSON & CO. INC AND

                   ARNHOLD AND S. BLEICHROEDER ADVISERS, LLC,

          EACH ON BEHALF OF ITS OWN AND WITH RESPECT TO SHARES OWNED BY

                            THE INVESTMENT FUNDS AND

                         SEPARATE ACCOUNTS MANAGED BY IT

                                 as the Sellers


              -----------------------------------------------------
                      SHARE PURCHASE AND TRANSFER AGREEMENT

                            AND SETTLEMENT AGREEMENT
              -----------------------------------------------------
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THIS SHARE PURCHASE AND TRANSFER AGREEMENT AND SETTLEMENT AGREEMENT (this
"AGREEMENT") is made on August 19, 2005

BETWEEN:

(1)   CELANESE EUROPE HOLDING GMBH & CO. KG, a limited partnership
      (Kommanditgesellschaft) organized under the laws of the Federal Republic
      of Germany with registered office (Sitz) at Kronberg i.T., registered with
      the commercial register of the Local Court (Amtsgericht) Koenigstein,
      Germany, under registration number HRA 2970 (the "PURCHASER")

AND

(2)   PAULSON & CO. INC., a corporation organized under the laws of the State of
      Delaware, with its principal offices at 590 Madison Avenue, New York, NY
      10022, USA ("PAULSON"), acting on its own behalf as well as with respect
      to the Shares (as defined below) owned by the investment funds and
      separate accounts managed by it; and

(3)   ARNHOLD AND S. BLEICHROEDER ADVISERS, LLC, a limited liability company
      established under the laws of the State of Delaware, with its principal
      offices at 1345 Avenue of the Americas, New York, NY 10105, USA ("ASB" and
      together with Paulson, the "SELLERS"), acting on its own behalf as well as
      with respect to the Shares (as defined below) owned by the investment
      funds and separate accounts managed by it.

The Sellers and the Purchaser are also collectively referred to hereinafter as
the "PARTIES" and each individually as a "PARTY".

PREAMBLE:

A.    Pursuant to a voluntary public takeover offer (the "TENDER OFFER") the
      Purchaser acquired in April 2004 approximately 82.6% of the outstanding
      shares in Celanese Aktiengesellschaft, a stock corporation organized under
      the laws of the Federal Republic of Germany, with registered office (Sitz)
      in Kronberg i.T., Germany, registered with the commercial register of the
      Local Court Koenigstein under registration number HRB 5277 (the
      "COMPANY").

B.    The registered share capital of the Company in the nominal amount of EUR
      140,069,354 is divided into 54,790,369 registered shares with no par value
      (auf den Namen lautende Stuckaktien) (the "SHARES"). The Shares are
      admitted to trading on the official market (Amtlicher Markt) of the
      Frankfurt Stock Exchange. The Shares are traded on the Frankfurt Stock
      Exchange and through the electronic trading system XETRA under the symbol
      "CZZ", under the German Securities Identification Number
      (Wertpapierkennnummer) (WKN) 575 300 and under the International
      Securities Identification Number (ISIN) DE 0005753008. The Shares were
      delisted from the New York Stock Exchange on June 2, 2004.

C.    On June 22, 2004, the Purchaser and the Company entered into a domination
      and profit and loss transfer agreement (Beherrschungs- und
      Gewinnabfuhrungsvertrag) (the "DOMINATION AGREEMENT"). The Domination
      Agreement was submitted to a shareholder vote, and approved, at an
      extraordinary general meeting of the Company held on July 30 and 31, 2004
      (the "EGM"). The Domination Agreement was registered in the commercial
      register of the Local Court of Koenigstein im Taunus on August 2, 2004
      and, under


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      the terms thereof, became operative on October 1, 2004. In connection with
      the Domination Agreement, the Purchaser has offered, pursuant to a
      mandatory offer required by Section 305(1) of the German Stock Corporation
      Act, the minority shareholders (ausstehende Aktionare) of the Company a
      "fair cash compensation" (angemessene Barabfindung) in exchange for their
      Shares in the amount of EUR 41.92 per Share (the "MANDATORY OFFER"). In
      addition, under the Domination Agreement, pursuant to Section 304(1),
      sentence 1 of the German Stock Corporation Act, any minority shareholder
      who elects not to tender its Shares into the Mandatory Offer and to remain
      a shareholder of the Company is entitled to receive a certain guaranteed
      fixed annual dividend (Ausgleich) per Share in lieu of any future dividend
      payments.

D.    Following the EGM, certain minority shareholders of the Company, whose
      names are set forth in Annex A (the "ORIGINAL PLAINTIFFS") brought forward
      legal actions with the Frankfurt District Court (Landgericht) and
      requested the court to set aside the shareholder resolutions passed at the
      EGM (collectively, the "ORIGINAL ACTIONS"). Several minority shareholders
      have joined the Original Actions via third party interventions in support
      of the Original Plaintiffs. The Purchaser has joined the proceedings via a
      third party intervention in support of the Company. In September 2004, the
      Frankfurt District Court consolidated the Original Actions (file no. 3-05
      O 112/04). One minority shareholder, Metropol Vermoegensverwaltungs- und
      Grundstuecks-GmbH, Cologne, Germany (the "AVOIDANCE PLAINTIFF" and
      together with the Original Plaintiffs, the "PLAINTIFFS"), brought forward
      an additional action (file no. 3-05 O 61/05) with the Frankfurt District
      Court and requested the court to rule that the shareholder resolutions
      passed at the EGM were void (Nichtigkeitsklage) (the "AVOIDANCE
      PROCEEDINGS"). In addition, several minority shareholders (including
      Paulson and the Plaintiffs) have initiated special award proceedings
      (Spruchverfahren) seeking the court's review of the amounts of the fair
      cash compensation and the guaranteed fixed annual dividend offered under
      the Domination Agreement (collectively, the "AWARD PROCEEDINGS"). In March
      2005, the Frankfurt District Court dismissed the motions of all minority
      shareholders regarding the initiation of the Award Proceedings as
      inadmissible. The ruling of the court is, however, subject to pending
      appeals (sofortige Beschwerden) (collectively, the "APPEALS") including
      appeals of Paulson and the Plaintiffs with the Frankfurt Higher District
      Court (Oberlandesgericht).

E.    A ratification resolution (Bestatigungsbeschluss) to ratify the
      shareholders' resolutions passed at the EGM was submitted to a shareholder
      vote, and approved, at the annual general meeting of the Company held on
      May 19 and 20, 2005 (the "AGM"). Following the AGM, several minority
      shareholders of the Company (including Paulson and the Plaintiffs) brought
      forward legal actions with the Frankfurt District Court against the
      shareholders' resolutions passed at the AGM as well, and requested that
      the court set aside the ratification resolution (collectively, the
      "ADDITIONAL ACTIONS"). In June 2005, the Frankfurt District Court has
      suspended the proceedings regarding the Original Actions until a
      judicially final and binding decision is rendered with regard to the
      Additional Actions and consolidated the Additional Actions (file no. 3-05
      O 71/05).

F.    In addition to the Original Actions, the Avoidance Action, the Award
      Proceedings, the Appeals and the Additional Actions, certain minority
      shareholders have instituted the legal proceedings set forth in Annex B
      against, among others, the Company and the Purchaser in connection with
      the Tender Offer and the Domination Agreement (these proceedings together
      with the Original Actions, the Avoidance Action, the Award Proceedings,
      the Appeals and the Additional Actions, and together with any and all
      other legal proceedings commenced against the Company or the Purchaser or
      any of their affiliates before, on or


                                                                           - 3 -
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      after the date hereof relating in any way to the subject matter of any of
      the foregoing, the "LEGAL PROCEEDINGS").

G.    As of today, Paulson and the investment funds and separate accounts
      managed by it own in the aggregate 5,758,299 Shares (the "PAULSON
      SHARES"), representing approximately 11.43% of the outstanding shares of
      the Company; and ASB and the investment funds and separate accounts
      managed by it own in the aggregate 160,000 Shares (the "ASB SHARES" and
      together with the Paulson Shares, the "SELLERS' SHARES"), representing
      approximately 0.32% of the outstanding Shares of the Company. The Sellers'
      Shares are currently held in book entry form within the Clearstream
      Banking AG booking system in various securities accounts of the Sellers
      and of the investment funds and separate accounts managed by the Sellers.

IT IS AGREED as follows:

1.    SUBJECT MATTER OF THIS AGREEMENT; CONDITION PRECEDENT

      The subject matter of this Agreement is (i) the sale and transfer of all
      Shares held by the Sellers and the investment funds and separate accounts
      managed by the Sellers to the Purchaser as well as (ii) the settlement of
      all Legal Proceedings, to the extent the Sellers are a party to the Legal
      Proceedings; (iii) the agreement by the Sellers not to make future
      investments in the Company; and (iv) a general release relating to their
      investment in the Company.

2.    SALE AND PURCHASE OF SHARES

2.1   Paulson hereby sells to the Purchaser, and the Purchaser hereby purchases
      from Paulson, the Paulson Shares; and ASB hereby sells to the Purchaser,
      and the Purchaser hereby purchases from ASB, the ASB Shares. For the
      avoidance of doubt, the sale and purchase of the Sellers' Shares pursuant
      to this Agreement shall include all Shares held, directly or indirectly,
      by the Sellers and the investment funds and separate accounts managed by
      them, irrespective of whether the description of the Shares and the
      Sellers' Shares set forth in recitals B and G of the Preamble or elsewhere
      herein is true and complete.

2.2   The sale and purchase of the Sellers' Shares contemplated by this
      Agreement shall be made with all rights attached to the Sellers' Shares
      (the "ANCILLARY RIGHTS"), including, without limitation, the rights to
      receive dividends and all subscription rights (Bezugsrechte). The right to
      receive dividends shall include the right to receive, in part or in total,
      the guaranteed fixed annual dividend for the current fiscal year 2004/2005
      as well as the right to receive dividends for all previous fiscal years of
      the Company, to the extent that profits of previous fiscal years have not
      been distributed as of the date hereof. The Ancillary Rights shall also
      include any right to participate in an increase of the amount of the fair
      cash compensation and/or the guaranteed fixed annual payment as a result
      of, or in connection with the Award Proceedings or other proceedings or
      agreements irrespective of whether such increase occurs through a court
      ruling, an agreement amongst the parties to the Award Proceedings or
      otherwise.

3.    PURCHASE PRICE

3.1   The purchase price for the Sellers' Shares amounts to EUR 51.00 per share
      (the "BASE PURCHASE PRICE"). In addition to the Base Purchase Price and as
      consideration for the Sellers' undertakings and the settlement set forth
      in Section 7 below, the Sellers shall be


                                                                           - 4 -
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      entitled to an additional payment of EUR 2.00 per share (the "ADDITIONAL
      PURCHASE PRICE"). Thus, the aggregate purchase price (i.e., Base Purchase
      Price and Additional Purchase Price) for the 5,758,299 Shares sold by
      Paulson amounts to EUR 305,189,847.00 (the "PAULSON PURCHASE PRICE"); and
      the aggregate purchase price (i.e., Base Purchase Price and Additional
      Purchase Price) for the 160,000 Shares sold by ASB amounts to EUR
      8,480,000.00 (the "ASB PURCHASE PRICE").

3.2   The Purchaser shall pay the Paulson Purchase Price and the ASB Purchase
      Price in accordance with the provisions of Section 4 below to bank
      accounts of the Sellers specified by the Sellers (the "SELLERS' BANK
      ACCOUNTS").

      A credit made to the Sellers' Bank Accounts shall have the effect of
      discharging the Purchaser in a corresponding amount from its obligation
      (schuldbefreiende Wirkung) to pay the Purchase Price to the respective
      Seller.

4.    TRANSFER OF SHARES

4.1   The Sellers' Shares are hereby assigned and transferred as follows:

      (a)   Paulson, on its own behalf and on behalf of the investment funds and
            separate accounts managed by it, hereby assigns and transfers to the
            Purchaser who accepts such transfer and assignment, the Paulson
            Shares, which transfer and assignment shall include all Ancillary
            Rights attached to the Paulson Shares.

      (b)   ASB, on its own behalf and on behalf of the investment funds and
            separate accounts managed by it, hereby assigns and transfers to the
            Purchaser who accepts such transfer and assignment, the ASB Shares,
            which transfer and assignment shall include all Ancillary Rights
            attached to the ASB Shares.

      The assignment and transfer of the Paulson Shares shall, however, be
      subject to the condition precedent of complete payment of the Paulson
      Purchase Price by the Purchaser to the bank accounts specified by Paulson;
      and the assignment and transfer of the ASB Shares shall, however, be
      subject to the condition precedent of complete payment of the ASB Purchase
      Price by the Purchaser to the bank accounts specified by ASB (each, a
      "CONDITION TO TRANSFER OF TITLE").

4.2   In order to ensure transfer of title in the Sellers' Shares, the Parties
      shall take the following actions concurrently (Zug um Zug) as soon as the
      Sellers have fully complied with their obligations under Section 7.1(a):

      (a)   The Sellers shall procure that (i) the Paulson Shares are
            transferred to the securities deposit of the Purchaser specified by
            the Purchaser (the "PURCHASER'S SECURITIES DEPOSIT") by making a
            corresponding book-entry transfer (Girosammelgutschrift)
            concurrently (Zug um Zug) with the payment by the Purchaser of the
            Paulson Purchase Price into the Paulson bank accounts; and (ii) the
            ASB Shares are transferred to the Purchaser's Securities Deposit by
            making a corresponding book-entry transfer (Girosammelgutschrift)
            concurrently with the payment by the Purchaser of the ASB Purchase
            Price into the ASB bank accounts.

      (b)   The Purchaser shall irrevocably instruct its bank in writing to (i)
            transfer the Paulson Purchase Price from its cash account with its
            bank to the Paulson bank accounts free of any bank charges, by wire
            transfer in immediately available funds in Euro concurrently with
            the transfer of the Paulson shares to the Purchaser's Securities


                                                                           - 5 -
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            Deposit; and (ii) transfer the ASB Purchase Price from its cash
            account with its bank to the ASB bank accounts free of any bank
            charges, by wire transfer in immediately available funds in Euro
            concurrently with the transfer of the ASB shares to the Purchaser's
            Securities Deposit.

      (c)   The Parties shall take any other action, make any other declaration
            and execute any such document which is required or which the
            Purchaser reasonably requests to be executed in order to transfer
            title in the Sellers' Shares to the Purchaser.

4.3   The Parties agree that, from the execution hereof and until the occurrence
      of the transfer of the Sellers' Shares to the Purchaser's Securities
      Deposit by way of book entry transfer, the Sellers shall hold the Sellers'
      Shares in custody for the Purchaser, free of any charges or costs.

5.    REPRESENTATIONS AND WARRANTIES

5.1   Each Seller hereby represents and warrants severally by way of an
      independent guarantee (selbstandiges Garantieversprechen) pursuant to
      Section 311(1) German Civil Code (Burgerliches Gesetzbuch ), except as
      otherwise is expressly provided for herein, as of the date hereof and, if
      different, as of the date when the transfer of the Shares pursuant to
      Section 4 above becomes effective, as follows:

      (a)   Paulson represents and warrants that it is a corporation duly
            organized, validly existing and in good standing under the laws of
            the State of Delaware. ASB represents and warrants that it is a
            limited liability company duly organized, validly existing and in
            good standing under the laws of the State of Delaware.

      (b)   Each Seller represents and warrants that it has all requisite power
            and authority to execute and deliver this Agreement and to perform
            its obligations hereunder and to consummate the transactions
            contemplated hereby. Each Seller represents and warrants that the
            execution and delivery of this Agreement, the performance of such
            Seller's obligations hereunder and the consummation of the
            transactions contemplated hereby have been duly and validly
            authorized by all necessary corporate and other proceedings on the
            part of the respective Seller. Each Seller represents and warrants
            that this Agreement has been duly executed and delivered by such
            Seller, and assuming the due execution hereof by the Purchaser, this
            Agreement constitutes the legal, valid and binding obligation of
            such Seller in accordance with its terms.

      (c)   Each Seller represents and warrants that it or the investment funds
            and separate accounts managed by it have good and valid title to the
            Sellers' Shares sold and to be transferred by such Seller, free and
            clear of any liens, claims, encumbrances, security interests,
            options, pre-emptive, drag-along or tag-along rights, rights of
            first refusal or first offer, charges or restrictions of any kind
            (collectively, "LIENS"). Each of the Sellers represents and warrants
            that upon book-entry of the transfer of such Seller's Shares in the
            Purchaser's Security Deposit, good and valid title to such Seller's
            Shares sold and to be transferred by such Seller will pass to the
            Purchaser, free and clear of any Liens, except for Liens arising
            from acts of the Purchaser.

5.2   The Purchaser hereby represents and warrants by way of an independent
      guarantee (selbstandiges Garantieversprechen) pursuant to Section 311(1)
      German Civil Code (Burgerliches Gesetzbuch), except as otherwise is
      expressly provided for herein, as of the


                                                                           - 6 -
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      date hereof and, if different, as of the date when the transfer of the
      Shares pursuant to Section 4 above becomes effective, as follows:

      (a)   The Purchaser represents and warrants that it is a limited
            partnership (Kommanditgesellschaft) organized, validly existing and
            in good standing under the laws of the Federal Republic of Germany.

      (b)   The Purchaser represents and warrants that it has all requisite
            power and authority to execute and deliver this Agreement and to
            perform its obligations hereunder and to consummate the transactions
            contemplated hereby. The Purchaser represents and warrants that the
            execution and delivery of this Agreement, the performance of its
            obligations hereunder and the consummation of the transactions
            contemplated hereby have been duly and validly authorized by all
            necessary corporate and other proceedings on its part. The Purchaser
            represents and warrants that this Agreement has been duly executed
            and delivered by it, and assuming the due execution hereof by the
            Sellers, this Agreement constitutes the legal, valid and binding
            obligation of the Purchaser in accordance with its terms.

6.    REMEDIES

6.1   If it becomes apparent that one or several of the representations and
      warranties given by the Sellers in this Agreement are not accurate or
      incomplete or in case of a breach of any of the other obligations of the
      Sellers under this Agreement, then the Purchaser may at its sole
      discretion request from the Sellers - who shall be liable for their
      respective obligations severally (teilschuldnerisch) - either

      (a)   that the respective Seller put the Purchaser into the position the
            Purchaser would be in had the relevant representations and
            warranties been correct and complete or the relevant obligation not
            been breached, as the case may be; or

      (b)   compensation for the damages (Schadensersatz wegen Nichterfullung)
            incurred by the Purchaser because of the inaccuracy or
            incompleteness of the relevant representations and warranties or the
            breach of the relevant obligation, as the case may be, provided,
            however, that the Purchaser shall only be entitled to be compensated
            for damages after (i) the Purchaser has granted the respective
            Seller a period of at least 10 calendar days in which to bring about
            the position the Purchaser would be in had the relevant
            representations and warranties been correct and complete or the
            relevant obligation not been breached, as the case may be, (each, a
            "RECTIFICATION") and the respective Seller fails to do so within
            said time period or (ii) if Rectification is not possible or
            sufficient.

6.2   If it becomes apparent that one or several of the representations and
      warranties given by the Purchaser in this Agreement are not accurate or
      incomplete or in case of a breach of any of the other obligations of the
      Purchaser under this Agreement, then the Sellers may at their sole
      discretion request from the Purchaser either

      (a)   that the Purchaser put the Sellers into the position the Sellers
            would be in had the relevant representations and warranties been
            correct and complete or the relevant obligation not been breached,
            as the case may be; or

      (b)   compensation for the damages (Schadensersatz wegen Nichterfullung)
            incurred by the Sellers because of the inaccuracy or incompleteness
            of the relevant representations and warranties or the breach of the
            relevant obligation, as the case


                                                                           - 7 -
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            may be, provided, however, that the Sellers shall only be entitled
            to be compensated for damages after (i) the Sellers have granted the
            Purchaser a period of at least 10 calendar days in which to bring
            about the position the Sellers would be in had the relevant
            representations and warranties been correct and complete or the
            relevant obligation not been breached, as the case may be, (each, a
            "RECTIFICATION") and the Purchaser fails to do so within said time
            period or (ii) if Rectification is not possible or sufficient.

6.3   Except as otherwise provided for in this Agreement, any claim by the
      Purchaser or the Sellers, as the case may be, based on the incorrectness
      or incompleteness of the representations and warranties shall become
      time-barred (verjahrt) on December 31, 2008. With respect to all other
      claims of the Purchaser against the Sellers or the Sellers against the
      Purchaser, as the case may be, and except as otherwise expressly provided
      for in this Agreement, the statutory limitation periods shall apply. With
      respect to the suspension (Hemmung) and interruption (Neubeginn) of the
      statute of limitations time periods set forth herein, the statutory regime
      applies.

6.4   Except as otherwise provided for in this Agreement and legally
      permissible, any claims of the Purchaser relating to avoidance
      (Anfechtung), rescission (Rucktritt) and the reduction of the Purchase
      Price (Minderung), as well as claims based on breach of pre-contractual
      duty (culpa in contrahendo, Section 311(2) BGB) shall be excluded, except
      to the extent such claims are the result of gross negligence or willful
      misconduct on the part of the Sellers.

7.    SELLERS' UNDERTAKINGS; SETTLEMENT

7.1   With respect to the purchase and acquisition of the Sellers' Shares by the
      Purchaser, the Sellers are prepared to accept the shareholders'
      resolutions passed at the EGM and the AGM and to acknowledge the legal
      effectiveness of the Domination Agreement. Therefore, the Sellers
      irrevocably undertake vis-a-vis the Purchaser and the Company (echter
      Vertrag zugunsten Dritter) to take the following actions without delay and
      hereby irrevocably makes the following declarations, as the case may be:

      (a)   Each of the Sellers shall, and shall procure that its affiliates,
            their respective past and current employees, officers, directors,
            representatives, agents, assigns, successors, predecessors, parents,
            subsidiaries, investors and shareholders, except to the extent such
            investors and shareholders are not acting with respect to an
            investment in such Sellers' investment funds and separate accounts
            (the "RELATED PARTIES"), irrevocably withdraw and abandon all
            actions, applications and appeals (Klage- bzw. Antragsrucknahme;
            Rucknahme von Rechtsmitteln) it brought forward in connection with
            the Tender Offer and the Domination Agreement, including in
            connection with the Legal Proceedings; and the Sellers hereby
            irrevocably waive the respective causes of action (Verzicht auf die
            geltend gemachten Anspruche).

      (b)   Each Seller on its own behalf and on behalf of its Related Parties
            hereby irrevocably waives any objections it might have against the
            legal effectiveness and validity or the lawfulness of the
            shareholders' resolutions passed at the EGM and the AGM, the
            Domination Agreement and the Tender Offer as well as any action
            taken under or in connection with the Domination Agreement and the
            Tender Offer. Each Seller shall take any action or make any
            additional declaration which the Purchaser or the Company reasonably
            requests from such Seller to maintain the legal effectiveness and
            registration of the Domination Agreement.


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      (c)   Each of the Sellers hereby acknowledges the effectiveness, validity
            and the lawfulness of the shareholders' resolutions passed at the
            EGM and the AGM, the Domination Agreement and the Tender Offer as
            well as any action taken under or in connection with the Domination
            Agreement and the Tender Offer. Each Seller shall, and shall procure
            that its Related Parties, refrain from taking any action (either in
            court or out of court) to challenge directly or indirectly the legal
            effectiveness and validity or the lawfulness of the shareholders'
            resolutions passed at the EGM and the AGM, the Domination Agreement
            and the Tender Offer as well as any action taken under or in
            connection with the Domination Agreement and the Tender Offer; each
            of the Sellers shall, and shall procure that its Related Parties,
            further refrain from initiating any other legal proceedings of
            whatever nature (including award proceedings), in any court or
            tribunal under the laws of any nation, state or territory, based on
            the alleged ineffectiveness, invalidity or unlawfulness of the
            shareholders' resolutions passed at the EGM and the AGM, the
            Domination Agreement and the Tender Offer as well as any action
            taken under or in connection with the Domination Agreement and the
            Tender Offer. Each of the Sellers shall, and shall procure that its
            Related Parties, also refrain from directly or indirectly supporting
            or encouraging any other person to take or to continue any such
            proceedings. In particular, each of the Sellers shall, and shall
            procure that its Related Parties, refrain from taking any action in
            connection with, and shall not directly or indirectly support any
            (existing or former) minority shareholder of the Company or any
            other person in connection with the Legal Proceedings or any other
            legal proceedings relating to the shareholders' resolutions passed
            at the EGM and the AGM, the Domination Agreement and the Tender
            Offer as well as any action taken under or in connection with the
            Domination Agreement and the Tender Offer. Each of the Sellers
            shall, and shall procure that its Related Parties, not make
            available any work product or other documentation prepared by
            itself, its affiliates or its former and present advisors (including
            legal advisors, accountants and financial advisors) related to or
            otherwise relevant for the Legal Proceedings to any other person.

      (d)   Each of the Sellers shall, and shall procure that its Related
            Parties, refrain from acquiring, directly or indirectly, any Shares
            or any other investment in the Company and shall, and shall procure
            that its Related Parties, not hold or otherwise control directly or
            indirectly any Shares or other investment in the Company in the
            future.

      (e)   Without limiting the generality of the foregoing, each of the
            Sellers shall, and shall procure that its Related Parties, refrain
            from taking any action (either in court or out of court) to
            challenge directly or indirectly any shareholders' resolutions or
            corporate decisions of the Company or to initiate any legal
            proceedings of whatever nature (including award proceedings) , in
            any court or tribunal under the laws of any nation, state or
            territory, in connection with such shareholders' resolutions or
            corporate decisions including, without limitation, in connection
            with an amendment of the Company's articles of association, a
            delisting of the Company, a squeeze-out or a conversion of the
            Company or any other type of restructuring of the Company (each, a
            "FUTURE TRANSACTION"). The Sellers shall also refrain, and shall
            procure that its Related Parties, from directly or indirectly
            supporting or encouraging any other person to take any action
            (either in court or out of court) to challenge or to continue to
            challenge, as the case may be, the legal effectiveness, validity or
            lawfulness of a Future Transaction or to initiate any legal
            proceedings of whatever nature (including award proceedings), in any
            court or tribunal under the laws of any nation, state or territory,
            in this connection.


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7.2   Upon withdrawal and abandonment by the Sellers of all actions and
      applications in accordance with Section 7.1(a), the Purchaser or the
      Company (as the case may be) shall, with respect to each such action,
      application and appeal, as the case may be, waive the initiation of
      proceedings regarding the determination of legal fees (Verzicht auf die
      Einleitung eines Kostenfestsetzungsverfahrens) with respect to the
      Sellers. The Purchaser and the Company will, however, not reimburse the
      Sellers for any costs, in particular lawyers', accountants' and other
      consultants' fees, incurred by the Sellers through such actions and
      applications or proceedings or the preparation thereof and the Sellers
      hereby irrevocably waive any claims in this respect.

7.3   Upon consummation of the sale and purchase of the Sellers' Shares in
      accordance with Section 4 above, all claims of the Sellers arising from
      and in connection with the Tender Offer and the Domination Agreement or
      any action taken under or in connection with the Domination Agreement and
      the Tender Offer are, except for the Parties' rights and obligations under
      this Agreement, settled (erledigt). In addition, each of the Sellers on
      behalf of itself and its Related Parties hereby irrevocably waives any and
      all actual or potential claims whatsoever (whether or not relating to the
      subject matter of the current Legal Proceedings) arising out of, or
      relating to the transactions or matters referred to directly or indirectly
      in this Agreement that such Seller has, or in the future may have, against
      the Purchaser, the Company or any of the Purchaser's or the Company's
      past, current and future Related Parties under the laws of any nation,
      state or territory. The Purchaser hereby accepts such waiver.

8.    PURCHASER'S UNDERTAKINGS; INCREASE OF FAIR CASH COMPENSATION

8.1   With respect to the sale and transfer of the Sellers' Shares by the
      Sellers and the settlement between the Parties in accordance with Section
      7 above, the Purchaser undertakes vis-a-vis the Sellers, subject to
      compliance with applicable law, to increase the fair cash compensation
      (Abfindung) under the Mandatory Offer of EUR 41.92 per Share resolved upon
      during the AGM (the "ORIGINAL CASH COMPENSATION") by an amount of EUR 9.08
      per Share (the "ADDITIONAL CASH COMPENSATION") up to an aggregate amount
      of EUR 51.00 per Share for all minority shareholders that accept the
      Mandatory Offer on or prior to September 29, 2005, provided, however, that
      a minority shareholder shall only be entitled to the Additional Cash
      Compensation if such shareholder irrevocably declares by signing a waiver
      declaration the form of which is attached as Annex C that such shareholder
      (i) has not filed or has withdrawn (as the case may be), and will not
      file, an application for the initiation of award proceedings, and
      irrevocably waives any and all rights to initiate and carry out award
      proceedings in connection with the Domination Agreement; (ii) has not
      adhered, and will not adhere, to applications and has not, or will not,
      facilitate award proceedings in connection with the Domination Agreement
      in any other way, whether directly or indirectly; and (iii) irrevocably
      waives any and all rights to participate in an increase of the amount of
      the fair cash compensation and/or the guaranteed fixed annual payment as a
      result of, or in connection with the Award Proceedings or other
      proceedings or agreements irrespective of whether such increase occurs
      through a court ruling, an agreement amongst the parties or otherwise.
      Minority shareholders who accept the Mandatory Offer after September 29,
      2005 shall not be entitled to receive the Additional Cash Compensation.

8.2   Notwithstanding the foregoing, for the avoidance of doubt and as a matter
      of utmost precaution the increase of the fair cash compensation under the
      Mandatory Offer shall be structured in a manner that, if the declarations
      described in the proviso to Section 8.1 above


                                                                          - 10 -
<PAGE>
      are not binding upon minority shareholders and the Original Cash
      Compensation is increased as a result of the Award Proceedings, other
      proceedings or agreements - irrespective of whether such increase occurs
      through a court ruling, an agreement amongst the parties to the relevant
      proceedings or otherwise - (the "COMPENSATION INCREASE"), the Additional
      Cash Compensation is to be credited against such Compensation Increase.
      Thus, the Additional Cash Compensation shall be deemed to be a prepayment
      on such Compensation Increase.

8.3   As long as the Purchaser complies with Sections 8.1 and 8.2, the
      undertakings of the Purchaser set forth in this Section 8 shall not
      prevent the Purchaser to enter into separate transactions with one,
      several or all minority shareholders and/or their representatives on terms
      and conditions deviating from the terms and conditions provided for in
      this Section 8.

9.    CONTINUED COOPERATION, CONFIDENTIALITY, PRESS RELEASES

9.1   The Parties agree to co-operate fully after the date hereof in order to
      consummate all the transactions intended by and/or envisaged in this
      Agreement. Each Party shall take such further actions, make such
      additional declarations and execute such documents as are necessary or, in
      the reasonable view of the Purchaser, appropriate to consummate the
      transactions intended by and/or contemplated in this Agreement.

9.2   The Parties shall treat the existence of this Agreement and its contents
      strictly confidential and shall make no public statements whatsoever
      concerning the existence of this Agreement and its contents.
      Notwithstanding the foregoing, it is acknowledged and agreed that (i) the
      Company and its affiliates may refer to this Agreement and describe its
      contents if and to the extent so required in order to implement the
      undertakings of the Purchaser set forth in Section 8 or by statutory law,
      regulation or order of a court, administrative agency or any other public
      authority, including, without limitation, in Form 8-K, amendments to its
      Schedule 13D, Schedule 13E-3, Form TO and other filings made pursuant to
      the U.S. Securities Exchange Act of 1934, as amended or the U.S.
      Securities Act of 1933, as amended; and (ii) each of the Sellers may refer
      to this Agreement and describe its contents to its shareholders and
      investors in accordance with past practice.

9.3   Upon execution of this Agreement, the Parties shall agree on the content
      and form of a press release with regard to the transactions and other
      agreements set forth herein. The Sellers shall not unreasonably withhold
      their consent to such or any other press releases prepared by the
      Purchaser and/or the Company. Until such press release is disseminated,
      the Sellers shall not communicate in any way with the press or any other
      media regarding this Agreement and the transactions contemplated hereby.
      In response to any unsolicited inquiry by the press or any other media
      regarding this Agreement and the transactions contemplated hereby, the
      Parties shall decline to comment. Following the dissemination of the press
      release, the Parties' only response to unsolicited inquiries by the press
      or any other media regarding the subject matter of this Agreement shall be
      that the transactions contemplated by this Agreement represent a fair
      resolution amongst the Parties with respect to the subject matter of this
      Agreement. Notwithstanding the foregoing, it is acknowledged and agreed
      that no Party shall make any adverse statements to the press or any other
      media about any other Party with respect to the subject matter of this
      Agreement.

10.   ASSIGNMENT

      None of the Sellers may not transfer any rights and obligations under or
      in connection with this Agreement without prior written consent of the
      Purchaser. The Purchaser has the right


                                                                          - 11 -
<PAGE>
      to only transfer its rights and obligations under this Agreement in whole
      or in part to one or more enterprises controlled by the Purchaser (each, a
      "TRANSFEREE") by way of assignment and assumption of this Agreement
      (Vertragsubernahme) (a "TRANSFER OF CONTRACT"). Upon the Transfer of
      Contract coming into effect, the Transferee fully assumes the contractual
      position of the Purchaser under this Agreement. The Sellers hereby grant
      its irrevocable consent to any Transfer of Contract. The Transfer of
      Contract shall become legally effective as of the receipt (Zugang) by the
      Sellers of a written declaration made by the Purchaser and the Transferee
      that a Transfer of Contract has occurred.

11.   LANGUAGE

      This Agreement is made in, and shall be construed in accordance with, the
      English language. In the event of a conflict between English terms and
      German terms immediately following in italics and in parenthesis in this
      Agreement, the German terms shall prevail.

12.   APPLICABLE LAW, JURISDICTION

12.1  This Agreement shall be governed by and interpreted exclusively in
      accordance with the laws of the Federal Republic of Germany with the
      exclusion of its conflict-of-laws provisions and the Convention on
      Contracts for the International Sale of Goods.

12.2  Frankfurt am Main, Germany shall be the exclusive place of jurisdiction
      for all disputes arising out of or in connection with this Agreement,
      provided, however, that the Purchaser may commence legal proceedings
      against the Sellers at any court that is competent (zustandig) for such
      proceedings.

13.   FEES AND EXPENSES

      Except as otherwise specifically set forth in this Agreement, the Parties
      hereto shall bear their respective expenses incurred with the preparation,
      execution and performance of this Agreement and the transactions
      contemplated therein, including all fees and expenses of their advisors
      and all fees and expenses incurred by each Party in connection with the
      Legal Proceedings.

14.   AMENDMENTS

      Any amendment or addition to this Agreement must be executed in writing,
      unless a more stringent form is required. This also applies to the
      deletion or amendment of this clause.

15.   ENTIRE AGREEMENT

      This Agreement sets out the entire agreement and understanding between the
      Parties with respect to the subject matter hereof and supersedes any and
      all earlier and current agreements, either orally or in writing, between
      the Parties.

16.   SEVERABILITY

      If one of the provisions of this Agreement is or becomes invalid or
      unimplementable, this shall not affect the validity of the remaining
      provisions. The Parties shall modify to the extent necessary or replace
      the invalid or unimplementable provision so that the effect of the
      modified or new provision corresponds as closely as possible to the
      intended effect of the invalid or unimplementable provision. In the event
      of an unintended omission in this


                                                                          - 12 -
<PAGE>
      Agreement, a provision shall be deemed agreed between the Parties which
      corresponds, on the basis of the purpose and the meaning of this Agreement
      and the Parties' intention, as closely as possible to the provision the
      Parties would have agreed upon had the Parties considered the matter at
      the outset.

17.   NOTICES, COMMUNICATION, EXERCISE OF RIGHTS

17.1  Any notice or other communication under this Agreement shall be effected
      in the English language and in writing and shall be delivered personally
      against confirmation of receipt or sent by "registered mail return receipt
      requested" or by an internationally recognized courier service or
      transmitted by facsimile (followed by confirmation delivered by
      "registered mail return receipt requested" or by an internationally
      recognized courier service) to the Parties at the followings addresses:

      If to the Sellers:

      Paulson & Co. Inc.
      590 Madison Avenue
      New York, NY 10022
      USA
      attn. General Counsel
      Fax no. +1 212 977 9505,

      and

      Arnhold and S. Bleichroeder Advisers, LLC
      1345 Avenue of the Americas
      New York, NY 10105
      USA
      attn.: General Counsel
      Fax no. +1 212 698 3271,

      with a copy to:

      Linklaters Oppenhoff & Radler
      Dr. Hans-Ulrich Wilsing
      Borsenplatz 1
      50667 Koln
      Germany
      Fax no. +49 221 2091 435.

      If to the Purchaser:

      Celanese Europe Holding GmbH & Co. KG
      Frankfurter Strasse 111
      61476 Kronberg i.T.
      Germany
      attn.: Management Board
      Fax no. + +49 69 305 82731 ,


                                                                          - 13 -
<PAGE>
      with a copy to:

      Gleiss Lutz
      Dr. Gerhard Wirth and Dr. Jan M. Bauer
      Maybachstrasse 6
      70469 Stuttgart
      Germany
      Fax no. +49 711 855 096,

      and a copy to

      Simpson Thacher & Bartlett LLP
      William R. Dougherty
      425 Lexington Avenue
      New York, NY 10017
      USA
      Fax no. +1 212 455 2502.

      The Sellers jointly on the one hand and the Purchaser on the other hand
      may change the addresses and fax numbers set forth above by giving a
      corresponding notice in accordance with this Section 17.1 indicating the
      new address and/or fax number, as the case may be, to which notices under
      this Agreement shall be delivered, provided, however, that such notice or
      a change of address shall be effective only upon receipt thereof.

17.2  Any amendments, consents, waivers, statements, declarations or notices of
      the Sellers under or in connection with this Agreement shall be validly
      made or given if made or given by Paulson. on behalf of all Sellers and
      Sellers hereby authorize Paulson to act in their name and on their behalf
      in making any and all such amendments, consents, waivers, statements,
      declarations and notices. The same shall apply to the exercise of any
      rights by the Sellers under or in connection with this Agreement.

                           [Signature Page to Follow.]


                                                                          - 14 -
<PAGE>
This Agreement is signed in New York, USA, on August 19, 2005 by and on behalf
of the Parties as follows:

Paulson & Co. Inc.:


By:      __________________________         By:      __________________________
         Name:                                       Name:
         Title:                                      Title:

Arnhold and S. Bleichroeder Advisers, LLC:


By:      __________________________         By:      __________________________
         Name:                                       Name:
         Title:                                      Title:

Celanese Europe Holding GmbH & Co. KG
By:      Its general partner
         Celanese Europe Management GmbH:


By:      __________________________         By:      __________________________
         Name:                                       Name:
         Title:                                      Title:


                                                                            -15-
<PAGE>
                                     ANNEX A

                          NAMES OF ORIGINAL PLAINTIFFS

     -    Richard Mayer
     -    Jochen Knoesel
     -    Allerthal Werke AG and Christa Gotz
     -    Carthago Value Invest AG
     -    Prof. Dr. Ekkehard Wenger
     -    Jens-Uwe Penquitt & Claus Deininger Vermogensverwaltung GbR
     -    Dr. Leonhard Knoll
     -    B.E.M. Borseninformations- und Effektenmanagement GmbH
     -    Protagon Capital GmbH


                                                                            -16-
<PAGE>
                                     ANNEX B

                             OTHER LEGAL PROCEEDINGS

I.   TENDER OFFER PROCEEDINGS (ANFECHTUNG DES AKTIENKAUFS IM RAHMEN DES
     UBERNAHMEVERFAHRENS)

<TABLE>
<CAPTION>
                                                                FILE NUMBER              FILE NUMBER
       PLAINTIFF                    DEFENDANT                (FIRST INSTANCE)         (COURT OF APPEAL)
<S>                     <C>                                  <C>                      <C>
     Richard Mayer      -     Celanese Europe Holding         3-06 O 181/04              5 U 131/05
                              GmbH & Co. KG

                        -     Claudio Sonder
</TABLE>

II.  PUBLIC REGISTER PROCEEDINGS (AMTSLOSCHUNGSVERFAHREN)

1.   PUBLIC REGISTER PROCEEDINGS WITH THE KONIGSTEIN LOCAL COURT (AMTSGERICHT)

<TABLE>
<CAPTION>
                PLAINTIFFS                             DEFENDANT                       FILE NUMBER
<S>                                                   <C>                              <C>
Richard Mayer                                         Celanese AG                      80 HRB 5277

OCP Obay Capital Pool Vermogens-                      Celanese AG                      80 HRB 5277
verwaltungsgesellschaft mbH
and Protagon Capital GmbH
</TABLE>

2.   PUBLIC REGISTER PROCEEDINGS WITH THE FRANKFURT DISTRICT COURT (LANDGERICHT)

<TABLE>
<CAPTION>
                                                               FILE NUMBER                FILE NUMBER
           PLAINTIFF                   DEFENDANT             (FIRST INSTANCE)          (COURT OF APPEAL)
<S>                                   <C>                    <C>                       <C>
         Richard Mayer                Celanese AG              3-16 T 25/04               20 W 425/04
</TABLE>


                                                                            -17-
<PAGE>
                                     ANNEX C

                         WAIVER LETTER (GERMAN VERSION)

                               VERZICHTSERKLARUNG

von _____________________________________, Wohnort/Sitz in ____________________,

_______________________________________________________________________________:


Mir/der von mir vertretenen Gesellschaft

     -    gehoren _______ Aktien der Celanese AG, die ich im Rahmen des
          Beherrschungs- und Gewinnabfuhrungsvertrags gegen Zahlung der
          festgelegten Abfindung einreiche;

     -    gehorten _______Aktien der Celanese AG, die ich im Rahmen des
          Beherrschungs- und Gewinnabfuhrungsvertrags gegen Zahlung der
          festgelegten Abfindung bereits eingereicht habe.

1.   Ich erklare gegenuber Celanese Europe Holding GmbH & Co. KG, dass ich/die
     von mir vertretene Gesellschaft im Zusammenhang mit dem Beherrschungs- und
     Gewinnabfuhrungsvertrag vom 22. Juni 2004

     -    keinen Antrag auf Einleitung eines Spruchverfahrens gemaB Section
          1 Nr. 1 Spruchverfahrensgesetz gestellt habe oder stellen werde oder
          einen bereits gestellten Antrag unwiderruflich und rechtsverbindlich
          zuruckgenommen habe und dass ich auf die Einleitung und Durchfuhrung
          eines Spruchverfahrens zur Bestimmung der angemessenen Barabfindung im
          Zusammenhang mit dem Ubertragungsbeschluss verzichte;

     -    Antragen nicht beitreten werde und ein Spruchverfahren
          gemaB Section 1 Nr. 1 Spruchverfahrensgesetz auch nicht in
          sonstiger Weise unmittelbar oder mittelbar fordern werde;


                                                                            -18-
<PAGE>
     -    auf eine in einem Spruchverfahren gemaB Section 1 Nr. 1
          Spruchverfahrensgesetz gerichtlich festgesetzte Abfindung oder zur
          Beendigung eines solchen Spruchverfahrens vereinbarte Abfindung
          verzichte.

_______________, den ______________ 2005


___________________________________


                                                                            -19-