Subscription Agreement, dated August 19, 2004


 Exhibit 4.21 
  
  
 Private Placement of up to 

U.S. $20,000,000 Principal Amount of Harken Energy Corporation 
 5% Senior Convertible Notes due 2009 
  
 Subscription Agreement 
  
 1.
Delivery of Documents. 
  

	 	(a)	Delivery of Documents by Harken. The following documents have been delivered or otherwise made available to the undersigned in connection with the offer and sale by Harken
Energy Corporation (“Harken” or the “Company”) to the undersigned Buyer (“Buyer”) of its 5% Senior Convertible Notes due 2009 with principal amount of up to $20,000,000 (the “Notes”), pursuant to Regulation D
of the United States Securities Act of 1933: 

  

							
	 	 	(1)	  	Exhibit A:	  	Private Placement Agreement;
				
	 	 	(2)	  	Exhibit B:	  	Copies of the Company’s Annual Report on Form 10-K for the year ended December 31, 2003 and all subsequent filings of Harken with the United States Securities and Exchange Commission have
been made available to the Buyer at the Company’s website at www.harkenenergy.com.
			
	 	 	(3)	  	The Private Offering Memorandum dated July 21, 2004, which contains a form of the Notes, attached as
Appendix A thereto and incorporated therein by reference.
				
	 	 	(4)
	  	Exhibit C:	  	The Officer’s Certificate of Buyer.

  

	 	(b)	Delivery of Documents by Buyer. The Officer’s Certificate of Buyer shall be deemed to have been executed by the Buyer and delivered to the Company as of the date hereof
and the facts set forth therein shall be deemed to be certified upon the execution by the Buyer of this agreement. 

  
 2. General 
  

	 	(a)	Capitalized terms not defined herein shall have the meanings set forth in the Private Placement Agreement. The Buyer is encouraged to read the documents referred to above very
carefully in regard to a potential investment in the Notes and the common stock of the Company (“Common Stock”) into which the Notes are convertible, and by signing below will agree with Harken that it has done so.


  

	 	(b)	The Company strongly urges the Buyer carefully to read the language contained under the heading “Risk Factors” in the Private Offering Memorandum for certain risk
factors with respect to an investment in securities of the Company. The Buyer acknowledges that it has read and understands such risk factors and statements. 

  
 3. Subscription Terms. 
  

	 	(a)	Subscription. The Buyer hereby subscribes for and agrees to purchase $ 5,245,000 in principal amount of the Notes for a total cash consideration value (“Consideration
Value”) equal to the nominal amount of the Notes subscribed. 








	 	(b)	Company Wire Instructions. The Consideration Value specified in paragraph 3(a) must be delivered to the following account of the Common Depository on behalf of the Company on
the Closing Date: 

  

			
	 Name of Common
Depository
	  	The Bank of New York
	 Euroclear Account ID Number
	  	95326
	 Clearstream Account ID Number
	  	80199
	 Common Code
	  	019458431
	 ISIN No
	  	XS0194584313
	 Swiss Securities No
	  	To be notified
	 Trade Date
	  	4 August 2004
	 Settlement Date
	  	6 August 2004

  

	 	(c)	Ownership of Shares. Neither the Buyer nor its affiliates are owners, beneficially or otherwise, of any Common Stock or other equity securities of the Company, or rights to
acquire Common Stock or other equity securities of the Company other than as set forth below: 

  
 (i) Ordinary shares of Common Stock:
            -0-             ; and 
  
 (ii) Other securities:
            -0-            . 
  

	 	(d)	Shares Outstanding and Reserved for Issuance. As of June 7, 2004, the Company had 206,238,087 shares of Common Stock issued and outstanding, 32,135,430 shares of Common Stock
reserved for issuance pursuant to securities exercisable or exchangeable for, or convertible into, shares of Common Stock and 296,372 shares of Series G-1, 27,150 shares of
 Series G-2, 77,517 shares of Series G-4, 50,000 share of
Series J and 50,000 shares of Series L Preferred Stock issued and outstanding as well as 8,300,034 warrants to purchase shares of Common Stock. 

  

	 	(e)	Notice to Buyer. Notices to Buyer shall be provided in accordance with the Private Placement Agreement to the following address: 

  

			
	 Name:*
	  	[GLOBAL CONVERTIBLE MEGATREND, LTD]
		
	 Address:
	  	[C/O FES First Equity Securities AG
	 	  	Bleicherweg 66
	 	  	CH-8022 Zurich
	 	  	www.fes.ch
	 	  	ATTN: Markus Mueller
	
	 Telephone No: +41-1-280-50-66

	
	 Fax No: +41-1-280-53-39


  
  







	 	(f)	Delivery of Notes. The global note certificate for the Notes will be delivered on the Closing Date to the Common Depository for Euroclear and Clearstream for credit to the
account of the Buyer set out below. 

  

			
	 Settlement System
(Euroclear/Clearstream)
	 	EUROCLEAR: 96718 or 92463*
	 Account ID Number
	 	*
	 Participant Name
	 	 Jefferies London or Credite
Agricole
 Luxembourg*

	 Common Code
	 	019458431
	 ISIN No:
	 	XS0194584313
	 Swiss Securities No:
	 	To be notified
	 Trade Date
	 	4 August 2004
	 Settlement Date
	 	6 August 2004

  

	4.	Private Placement Agreement Binding; Confirmations. When this agreement is signed below by the Buyer, (a) Harken and the Buyer agree that the Private Placement Agreement
attached as Exhibit A will be a valid and binding agreement between them, and (b) the Buyer will have confirmed to Harken its representations, covenants and acknowledgments contained in Sections 2 and 4 of such Private Placement Agreement.


  

	5.	Limitation of Dispositions. Neither the Notes nor the Company’s Common Stock issuable upon conversion of the Notes have been or will be registered with the United States
Securities Act of 1933, as amended (the “Securities Act”), except as described in the attached documents. Such securities may not be offered, converted or otherwise disposed of, unless they are registered under such Securities Act and any
applicable state securities laws or exemptions from the registration requirements of the foregoing securities laws are available. 

  

	
	BUYER: GLOBAL CONVERTIBLE MEGATREND
	
	 By: /S/

	 Name: Markus Mueller

	 Title: Manager

	 If applicable, Buyer’s Tax ID No.:  _____________

	 
	
	 Date: July 21, 2004

	
	 HARKEN ENERGY CORPORATION

	
	 By: /s/

	 Name: Elmer Johnston

	 Title: Vice President, Secretary and General Counsel

	
	 Date: August 19, 2004




 * Buyer to complete