EXHIBIT 21(a)

ENERGY FUTURE HOLDINGS CORP.

SUBSIDIARY HIERARCHY

Effective December 31, 2009



|                                           |  |             
|------------------------------------------ |  | ------------
|                                           |  | Jurisdiction
|Energy Future Holdings Corp.               |  | Texas       
|Energy Future Competitive Holdings Company |  | Texas       
|Texas Competitive Electric Holdings LLC    |  | Delaware    
|TCEH Finance, Inc.                         |  | Delaware    
|Generation MT Company LLC                  |  | Delaware    
|Luminant Holding Company LLC               |  | Delaware    
|Luminant Energy Company LLC                |  | Texas       
|Luminant ET Services Company               |  | Texas       
|Luminant Energy Trading California Company |  | Texas       
|Luminant Energy Trading Canada Limited     |  | Canada      
|Luminant Energy Services Company           |  | Texas       
|Luminant Generation Company LLC            |  | Texas       
|Nuclear Energy Future Holdings LLC         |  | Delaware    
|Nuclear Energy Future Holdings II LLC      |  | Delaware    
|Comanche Peak Nuclear Power Company LLC1   |  | Delaware    
|Valley NG Power Company LLC                |  | Texas       
|Luminant Renewables Company LLC            |  | Texas       
|Generation SVC Company                     |  | Texas       
|Luminant Power Services Company            |  | Delaware    
|Big Brown 3 Power Company LLC              |  | Texas       
|Big Brown Power Company LLC                |  | Texas       
|Collin Power Company LLC                   |  | Delaware    
|DeCordova Power Company LLC                |  | Texas       
|Lake Creek 3 Power Company LLC             |  | Texas       
|Martin Lake 4 Power Company LLC            |  | Texas       
|Monticello 4 Power Company LLC             |  | Texas       
|Morgan Creek 7 Power Company LLC           |  | Texas       
|Oak Grove Management Company LLC           |  | Delaware    
|Oak Grove Power Company LLC                |  | Texas       
|Sandow Power Company LLC                   |  | Texas       
|Tradinghouse 3 & 4 Power Company LLC       |  | Texas       
|Tradinghouse Power Company LLC             |  | Texas       
|Valley Power Company LLC                   |  | Texas       
|Luminant Mining Services Company           |  | Delaware    
|Big Brown Lignite Company LLC              |  | Texas       
|Luminant Big Brown Mining Company LLC      |  | Texas       
|Luminant Mining Company LLC                |  | Texas       
|Oak Grove Mining Company LLC               |  | Texas       
|Luminant Mineral Development Company LLC   |  | Texas       
|NCA Resources Development Company LLC      |  | Texas       
|Wichita/Victory Avenue LLC                 |  | Texas       
|TXU Energy Retail Company LLC              |  | Texas       
|TXU Retail Services Company                |  | Delaware    
|TXU SESCO Company LLC                      |  | Texas       
|TXU SESCO Energy Services Company          |  | Texas       
|TXU Energy Solutions Company LLC           |  | Texas       
|TXU Chilled Water Solutions Company        |  | Texas       
|TXU SEM Company                            |  | Delaware    
|TXU Energy Retail Management Company LLC   |  | Delaware    



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|                                                    |  |                     
|--------------------------------------------------- |  | --------------------
|                                                    |  | Jurisdiction        
|Energy Future Intermediate Holding Company LLC      |  | Delaware            
|EFIH Finance Inc.                                   |  | Delaware            
|Oncor Electric Delivery Holdings Company LLC        |  | Delaware            
|Oncor Electric Delivery Company LLC2                |  | Delaware            
|Oncor Management Investment LLC3                    |  | Delaware            
|Oncor Electric Delivery Transition Bond Company LLC |  | Delaware            
|Oncor License Holdings Company LLC                  |  | Texas               
|Oncor Communications Holdings Company LLC           |  | Delaware            
|EFH Corporate Services Company                      |  | Texas               
|EFH CG Management Company LLC                       |  | Texas               
|EFH Communications Holdings Company LLC             |  | Delaware            
|Generation Development Company LLC                  |  | Delaware            
|NCA Development Company LLC                         |  | Texas               
|EFH Industries Company LLC                          |  | Delaware            
|EFH Properties Company                              |  | Texas               
|Communications License Holdings I Inc.              |  | Texas               
|EFH Investment Company                              |  | Texas               
|Basic Resources Inc.                                |  | Texas               
|TXU Receivables Company                             |  | Delaware            
|EFH CC Holdings Company LLC                         |  | Texas               
|EFH Vermont Insurance Company                       |  | Vermont             
|LSGT Gas Company LLC                                |  | Texas               
|LSGT Processing Company                             |  | Texas               
|Lone Star Energy Services, Inc                      |  | Texas               
|ENS Holdings I, Inc.                                |  | Texas               
|ENS Holdings II, Inc.                               |  | Texas               
|ENS Holdings Limited Partnership4                   |  | Texas               
|LSGT SACROC, Inc.5                                  |  | Texas               
|LSGT Finance (II), Inc.                             |  | Texas               
|LSGT House Inc.                                     |  | Texas               
|Enserch Finance N.V.                                |  | Netherlands Antilles
|LSGT International Investments Limited              |  | Delaware            
|Humphreys & Glasgow Limited                         |  | United Kingdom      
|EEC Holdings, Inc                                   |  | Nevada              
|EECI, Inc.                                          |  | Nevada              
|Ebasco Services of Canada, Ltd                      |  | Canada              



|1 | 88% ownership interest
|- | ----------------------

|2 | 80.033% ownership interest
|- | --------------------------

|3 | Oncor Management Investment LLC owns 0.217% of Oncor Electric Delivery Company LLC. Regarding the ownership of Oncor Management Investment LLC, Oncor
Electric Delivery Company LLC owns 100% of the Class A membership interests. Certain management employees of Oncor Electric Delivery Company LLC own 100% of the Class B membership interests.
|- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|4 | 99% owned by ENS Holdings II, Inc. and 1% owned by ENS Holdings I, Inc.
|- | -----------------------------------------------------------------------

|5 | 0.35% owned by ENS Holdings Limited Partnership and 99.65% owned by LSGT Finance (II), Inc.
|- | -------------------------------------------------------------------------------------------