Form of Certificate




 Exhibit 4.21 
  
 [Front of Certificate] 
  
 GASTAR EXPLORATION LTD. 
 CONTINUED PURSUANT TO
THE BUSINESS CORPORATIONS ACT (ALBERTA) 
  
  

					
	_________	 	 	 	_________________
	 NUMBER
	 	 	 	COMMON SHARES
			
	 This Certifies That
	 	 	 	CUSIP 367299 10 4

  
 is the registered holder of

 fully paid and non-assessable Common Shares in the capital of 
  
 GASTAR EXPLORATION LTD. 
  
 transferable on the books of the corporation by the registered holder in person or by duly authorized attorney upon surrender of this Certificate properly endorsed.

  
 The class of shares represented by this Certificate is subject to certain
rights, privileges, restrictions and conditions and the Corporation will furnish to a shareholder, on demand and without charge, a full copy of the text of the rights, privileges, restrictions and conditions attached to each class authorized to be
issued and to each series in so far as they have been fixed by the directors, and the authority of the directors to fix the rights, privileges, restrictions and conditions of subsequent series 
  
 This Certificate is not valid until countersigned and registered by the Transfer Agent and
Registrar of the Corporation. 
  
 In witness Whereof the Corporation has caused
this Certificate to be signed by the facsimile signatures of its duly authorized officers. 
  
 Dated: 
  

									
	 	  	 	  	 COUNTERSIGNED AND REGISTERED:
 CIBC MELLON
TRUST COMPANY
 TRANSGFER AGENT AND REGISTRAR
	  	TORONTO, ONT.
				
	 	  	 	  	By:	  	  


	 	  	 	  	 	  	AUTHORIZED OFFICER
			
	 DIRECTOR
	  	 CHIEF FINANCIAL
 OFFICER
	  	THE SHARES REPRESENTED BY THIS CERTIFICATE ARE TRANSFERABLE AT THE OFFICES OF CIBC MELLON TRUST COMPANY OF CANADA, TORONTO, ONTARIO.









 [Reverse of Certificate] 
  
 FOR VALUE RECEIVED the undersigned hereby sells, assigns and transfers unto 
  
 PLEASE INSERT SOCIAL INSURANCE NUMBER 
  
  
 ____________________________________________________________ 
 (REVENUE CANADA REQUIRES THE S.I.N. OF THE TRANSFEREE) 
  
 __________________________________________________________________________________________________________ 
 (Name and address of
transferee) 
  
                                       
                                        
                                   shares registered in the name of the
undersigned on the books of the Corporation named on the face of this certificate and represented hereby, and irrevocably constitutes and appoints 
  
                                       
                                        
                                   the attorney of the undersigned to
transfer the said shares on the register of transfers and books of the Corporation with full power of substitution hereunder. 
  
 DATED: 
  

			
	
	  	

	(Signature of Witness)	  	(Signature of Shareholder)

  
 NOTICE: THE SIGNATURE OF THIS
ASSIGNMENT MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR WITHOUT ALTERATION OR ENLARGEMENT, OR ANY CHANGE WHATEVER. 
  
 THE SIGNATURE OF THE TRANSFEROR MUST BE GUARANTEED BY A BANK, TRUST COMPANY OR REGISTERED 
 SECURITIES DEALER. 
  

	
	 SIGNATURE GUARANTEED BY: