FORM 4
[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
                                                                                  
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
                      

1. Name and Address of Reporting Person *

BLACKSTONE MANAGEMENT ASSOCIATES CAYMAN IV LP
2. Issuer Name and Ticker or Trading Symbol

Celanese CORP [ CE ]
5. Relationship of Reporting Person(s) to Issuer (Check all applicable)

_____ Director                      __ X __ 10% Owner
_____ Officer (give title below)      _____ Other (specify below)
(Last)          (First)          (Middle)

C/O THE BLACKSTONE GROUP, 345 PARK AVENUE
3. Date of Earliest Transaction (MM/DD/YYYY)

4/7/2005
(Street)

NEW YORK, NY 10154
(City)        (State)        (Zip)
4. If Amendment, Date Original Filed (MM/DD/YYYY)

 
6. Individual or Joint/Group Filing (Check Applicable Line)

___ Form filed by One Reporting Person
_ X _ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Series A common stock, par value $0.0001 per share   4/7/2005     C (1)    57051899   (1) A $0   61357578   I   See footnotes   (1) (2) (3) (4) (5) (6) (7)
Series A common stock, par value $0.0001 per share   4/7/2005     C (1)    3956713   A $0   (1) 4255324   I   See footnotes   (1) (2) (3) (4) (5) (6) (7)
Series A common stock, par value $0.0001 per share   4/7/2005     C (1)    31018837   A $0   (1) 33359813   I   See footnotes   (1) (2) (3) (4) (5) (6) (7)

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Trans. Date 3A. Deemed Execution Date, if any 4. Trans. Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
6. Date Exercisable and Expiration Date 7. Title and Amount of Securities Underlying Derivative Security
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Explanation of Responses:
(1)  Represents shares of Series A common stock issued upon a mandatory conversion of all shared of Series B common stock pursuant to the certificate of incorporation of Celanese Corporation which conversion is exempt under Rule 16b-6(b) under the Securities Exchange Act of 1934, as amended (the "Exchange Act").
(2)  Blackstone Capital Partners (Cayman) Ltd. 1 ("Cayman 1"), Blackstone Capital Partners (Cayman) Ltd. 2 ("Cayman 2") and Blackstone Capital Partners (Cayman) Ltd. 3 ("Cayman 3" and, collectively with Cayman 1 and Cayman 2, the "Cayman Entities"), respectively own 61,357,578, 4,255,324 and 33,359,813 shares of the Series A common stock reported as beneficially owned in the above table. Blackstone Capital Partners (Cayman) IV L.P. ("BCP IV") owns 100% of Cayman 1. Blackstone Family Investment Partnership (Cayman) IV-A L.P. ("BFIP") and Blackstone Capital Partners (Cayman) IV-A L.P. ("BCP IV-A") collectively own 100% of Cayman 2. Blackstone Chemical Coinvest Partners (Cayman) L.P. ("BCCP" and, collectively with BCP IV, BFIP and BCP IV-A, the "Blackstone Funds") owns 100% of Cayman 3.
(3)  Each of the Blackstone Funds may be deemed to be the beneficial owner of the shares of Series A common stock held by the Cayman Entities owned by such Blackstone Funds. Blackstone Management Associates (Cayman) IV L.P. ("BMA") is the general partner of each of the Blackstone Funds and, therefore, may be deemed to be the beneficial owner of the shares of Series A common stock held by the Cayman Entities. Blackstone LR Associates (Cayman) IV Ltd. ("BLRA") is the general partner of BMA and may, therefore, be deemed to be the beneficial owner of the shares of Series A common stock held by the Cayman Entities.
(4)  Messrs. Peter G. Peterson and Stephen A. Schwarzman are directors and controlling persons of BLRA and, as such, may be deemed to share beneficial ownership of the shares of Series A common stock held by the Cayman Entities.
(5)  Due to the electronic system's limitation of 10 Reporting Persons per joint filing, this statement is being filed in duplicate.
(6)  Information with respect to each of the Reporting Persons is given solely by such Reporting Persons, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.
(7)  Pursuant to Rule 16a-1(a)(4) of the Exchange Act, each of the Reporting Persons, other than the Cayman Entities, herein states that this filing shall not be deemed an admission that he or it is the beneficial owner of any of the shares of Series A common stock covered by this Statement. Each of BLRA, BMA, Messrs. Peter G. Peterson and Stephen A. Schwarzman disclaims beneficial ownership of the Series A common stock, except to the extent of its or his pecuniary interest in such shares of Series A common stock.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
BLACKSTONE MANAGEMENT ASSOCIATES CAYMAN IV LP
C/O THE BLACKSTONE GROUP
345 PARK AVENUE
NEW YORK, NY 10154

X

BLACKSTONE CAPITAL PARTNERS CAYMAN IV LP
BLACKSTONE GROUP
345 PARK AVE
NEW YORK, NY 10154

X

BLACKSTONE FAMILY INVESTMENT PARTNERSHIP CAYMAN IV-A LP
BLACKSTONE GROUP
345 PARK AVE
NEW YORK, NY 10154

X

BLACKSTONE CAPITAL PARTNERS CAYMAN IV- A LP
BLACKSTONE GROUP
345 PARK AVE
NEW YORK, NY 10154

X

Blackstone Chemical Coinvest Partners (Cayman) L.P.
C/O THE BLACKSTONE GROUP
345 PARK AVENUE
NEW YORK, NY 10154

X


Signatures
__________________________, Director 4/8/2005
** Signature of Reporting Person Date


Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

Exhibit 99.1

Joint Filer Information

Date of Event Requiring

Statement: April 7, 2005

Issuer Name and Ticker or

Trading Symbol:               Celanese Corporation (CE)

Designated Filer:             Blackstone Management Associates
                                (Cayman) IV L.P.

Other Joint Filers:           Blackstone Capital Partners (Cayman) IV L.P.,
                              Blackstone Family Investment Partnership (Cayman)
                              IV-A L.P., Blackstone Capital Partners (Cayman)
                              IV-A L.P.,  Blackstone Chemical Coinvest
                              Partners  (Cayman) L.P.

Addresses:                    The principal business address of each of the
                              Joint Filers above is c/o The Blackstone Group,
                              345 Park Avenue, New York, New York 10154

Signatures:                   Blackstone Capital Partners (Cayman) IV L.P.

                              By:  Blackstone Management Associates (Cayman)
                                   IV L.P., its general partner

                                   By:  Blackstone LR Associates (Cayman) IV
                                        Ltd., its general partner

                                   By:  /s/ Robert L. Friedman
                                        ------------------------------
                                        Name:  Robert L. Friedman
                                        Title: Director

                              Blackstone Family Investment Partnership
                                (Cayman) IV-A L.P.

                              By:  Blackstone Management Associates (Cayman)
                                   IV L.P., its general partner

                                   By:  Blackstone LR Associates (Cayman) IV
                                        Ltd., its general partner

                                   By:  /s/ Robert L. Friedman
                                        ------------------------------
                                        Name:  Robert L. Friedman
                                        Title: Director

                              Blackstone Capital Partners (Cayman) IV-A L.P.

                              By:  Blackstone Management Associates (Cayman)
                                   IV L.P., its general partner

                                   By:  Blackstone LR Associates (Cayman) IV
                                        Ltd., its general partner

                                   By:  /s/ Robert L. Friedman
                                        ------------------------------
                                        Name:  Robert L. Friedman
                                        Title: Director

                              Blackstone Chemical Coinvest Partners (Cayman)
                                L.P.

                              By:  Blackstone Management Associates (Cayman) IV
                                   L.P., its general partner

                                   By:  Blackstone LR Associates (Cayman) IV
                                        Ltd., its general partner

                                   By:  /s/ Robert L. Friedman
                                        ------------------------------
                                        Name:  Robert L. Friedman
                                        Title: Director