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Exhibit 1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(f) of the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing on behalf of each of us of an amendment to Schedule 13D relating to the Ordinary Shares of Celanese AG, a German stock corporation, and that any subsequent amendments thereto filed by any of us will be filed on behalf of each of us. This Agreement may be included as an exhibit to such joint filing.

DATE: October 7, 2004

BCP CRYSTAL ACQUISITION GMBH & CO. KG
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BCP ACQUISITION GMBH & CO. KG
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BCP HOLDINGS GMBH
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BCP MANAGEMENT GMBH
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BCP CAYLUX HOLDINGS LUXEMBOURG S.C.A.
By:	BCP Caylux Holdings Ltd. 1, its manager
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BCP CAYLUX HOLDINGS LTD. 1
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BLACKSTONE CAPITAL PARTNERS (CAYMAN) IV L.P.

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By:	Blackstone Management Associates (Cayman) IV L.P., its general partner
By:	Blackstone LR Associates (Cayman) IV Ltd., its general partner
	By:	/s/ Chinh Chu
		Name: Chinh Chu
		Title: Authorized Person
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/ Chinh Chu
		Name: Chinh Chu
		Title: Authorized Person
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/ Chinh Chu
		Name: Chinh Chu
		Title: Authorized Person
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/ Chinh Chu
		Name: Chinh Chu
		Title: Authorized Person
BLACKSTONE MANAGEMENT ASSOCIATES (CAYMAN) IV L.P.
By:	Blackstone LR Associates (Cayman) IV Ltd., its general partner

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By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BLACKSTONE LR ASSOCIATES (CAYMAN) IV LTD.
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BLACKSTONE CRYSTAL HOLDINGS CAPITAL PARTNERS (CAYMAN) IV LTD.
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 1
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 2
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 3
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
BCP CRYSTAL HOLDINGS LTD. 2
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Authorized Person
CRYSTAL US HOLDINGS 3 L.L.C.
By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: Manager
BCP CRYSTAL US HOLDINGS CORP.

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By:	/s/ Chinh Chu
	Name: Chinh Chu
	Title: President
/s/ Peter G. Peterson
PETER G. PETERSON
/s/ Stephen A. Schwarzman
STEPHEN A. SCHWARZMAN