**Exhibit 31.01**

 

## **CERTIFICATION**

##  

I, Tim E.Taylor, certify that:

 

1.      I have reviewed this report on Form 10-K of Public ServiceCompany of Colorado;

 

2.                  Basedon my knowledge, this report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statementsmade, in light of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report;

 

3.                  Basedon my knowledge, the financial statements, and other financial informationincluded in this annual report, fairly present in all material respects thefinancial condition, results of operations and cash flows of the registrant asof, and for, the periods presented in this report;

 

4.                  Theregistrant’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant andhave:

 

a)        Designed such disclosure controls andprocedures or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to theregistrant, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which thisreport is being prepared;

 

b)        Designed such internal control over financialreporting, or caused such internal control over financial reporting to bedesigned under our supervision, to provide reasonable assurance regarding thereliability of financial reporting and the preparation of financial statementsfor external purposes in accordance with generally accepted accounting principles;

 

c)         Evaluated the effectiveness of the registrant’sdisclosure controls and procedures and presented in this report our conclusionsabout the effectiveness of the disclosure controls and procedures, as of theend of the period covered by this report based on such evaluation;

 

d)        Disclosed in this report any change in theregistrant’s internal control over financial reporting that occurred during theregistrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarterin the case of an annual report) that has materially affected or is reasonablylikely to materially affect, the registrant’s internal control over financialreporting; and

 

5.                  The registrant’s other certifyingofficer and I have disclosed, based on our most recent evaluation of internalcontrol over financial reporting, to the registrant’s auditors and the auditcommittee of the registrant’s board of directors (or persons performing theequivalent functions):

 

a)         All significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial information; and

 

b)        Any fraud, whether or not material, thatinvolves management or other employees who have a significant role in theregistrant’s internal control over financial reporting.

 
|        | /s/ TIM E. TAYLOR                     |
|--------|---------------------------------------|
|   | Tim E. Taylor                         |
|   | President and Chief Executive Officer |

 
| Date: February 25, 2008 |   |
|-----------------------------------|--------|

 

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