Joint Filing Agreement

EXHIBIT 1

Joint Filing Agreement

     In accordance with Rule 13d-1(k) promulgated under the U.S. Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with all other Reporting Persons (as such term is defined in the Schedule 13D referred to below) on behalf of each of them of a Statement on Schedule 13D (including amendments thereto) with respect to the Series A Common Stock, par value $0.0001 per share, of Celanese Corporation, a Delaware corporation, and that this Joint Filing Agreement may be included as an Exhibit to such joint filing. This Joint Filing Agreement may be executed in any number of counterparts, all of which together shall constitute one and the same instrument.

     IN WITNESS WHEREOF, the undersigned hereby execute this Agreement as of May 16, 2007.

BLACKSTONE CAPITAL PARTNERS (CAYMAN)
LTD. 1
 

By:  

Name:  

Title:  

BLACKSTONE CAPITAL PARTNERS (CAYMAN)
LTD. 2
 

By:  

Name:  

Title:  

BLACKSTONE CAPITAL PARTNERS (CAYMAN)
LTD. 3
 

By:  

Name:  

Title:  

BLACKSTONE CAPITAL PARTNERS (CAYMAN)
IV L.P.


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


By: Xxxxxxxxxx XX Associates (Cayman) IV Ltd.,
its general partner
 

By:  

Name:  

Title:  

	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:
		Name:
		Title:
	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:
		Name:
		Title:
	BLACKSTONE MANAGEMENT ASSOCIATES (CAYMAN) IV L.P. By: Xxxxxxxxxx XX Associates (Cayman) IV Ltd., its general partner
	By:
		Name:
		Title:
	XXXXXXXXXX XX ASSOCIATES (CAYMAN) IV LTD.
	By:
		Name:
		Title:
	BLACKSTONE MANAGEMENT PARTNERS IV L.L.C.
	By:	/s/  Xxxxxx X. Xxxxxxxx
		Name:	Xxxxxx X. Xxxxxxxx
		Title:	Director

Xxxxx X. Xxxxxxxx 

Xxxxxxx X. Xxxxxxxxxx