JOINT FILING AGREEMENT

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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/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BCP ACQUISITION GMBH & CO. KG
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BCP HOLDINGS GMBH
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BCP MANAGEMENT GMBH
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BCP CAYLUX HOLDINGS LUXEMBOURG S.C.A.
		By:		BCP Caylux Holdings Ltd. 1, its manager
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BCP CAYLUX HOLDINGS LTD. 1
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				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:		Xxxxxxxxxx XX Associates (Cayman) IV Ltd., its general partner
				By:		/s/ Xxxxx Xxx
						Name: Xxxxx Xxx
						Title: Authorized Person
		BLACKSTONE CAPITAL PARTNERS (CAYMAN) IV-A L.P.
		By:		Blackstone Management Associates (Cayman) IV L.P., its general partner
		By:		Xxxxxxxxxx XX Associates (Cayman) IV Ltd., its general partner
				By:		/s/ Xxxxx Xxx
						Name: Xxxxx Xxx
						Title: Authorized Person
		BLACKSTONE FAMILY INVESTMENT PARTNERSHIP (CAYMAN) IV-A L.P.
		By:		Blackstone Management Associates (Cayman) IV L.P., its general partner
		By:		Xxxxxxxxxx XX Associates (Cayman) IV Ltd., its general partner
				By:		/s/ Xxxxx Xxx
						Name: Xxxxx Xxx
						Title: Authorized Person
		BLACKSTONE CHEMICAL COINVEST PARTNERS (CAYMAN) L.P.
		By:		Blackstone Management Associates (Cayman) IV L.P., its general partner
		By:		Xxxxxxxxxx XX Associates (Cayman) IV Ltd., its general partner
				By:		/s/ Xxxxx Xxx
						Name: Xxxxx Xxx
						Title: Authorized Person
		BLACKSTONE MANAGEMENT ASSOCIATES (CAYMAN) IV L.P.
		By:		Xxxxxxxxxx XX Associates (Cayman) IV Ltd., its general partner

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		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		XXXXXXXXXX XX ASSOCIATES (CAYMAN) IV LTD.
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		XXXXXXXXXX XXXXXXX HOLDINGS CAPITAL PARTNERS (CAYMAN) IV LTD.
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 1
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 2
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 3
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		BCP CRYSTAL HOLDINGS LTD. 2
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Authorized Person
		CRYSTAL US HOLDINGS 3 L.L.C.
		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: Manager
		BCP CRYSTAL US HOLDINGS CORP.

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		By:		/s/ Xxxxx Xxx
				Name: Xxxxx Xxx
				Title: President
		/s/ Xxxxx X. Xxxxxxxx
		XXXXX X. XXXXXXXX
		/s/ Xxxxxxx X. Xxxxxxxxxx
		XXXXXXX X. XXXXXXXXXX