**Exhibit 31.1**

** **

**CERTIFICATION**

 

I, John M. Fox, certify that:

 

1. I have reviewed this quarterly report on Form 10-Q ofMarkWest Hydrocarbon, Inc.:

 

2. Based on my knowledge, this quarterly report does notcontain any untrue statement of a material fact or omit to state a materialfact necessary to make the statements made, in light of the circumstances underwhich such statements were made, not misleading with respect to the periodcovered by this quarterly report.

 

3. Based on my knowledge, the financial statements, and otherfinancial information included in this quarterly report, fairly present in allmaterial respects the financial condition, results of operations and cash flowsof the registrant as of, and for, the periods presented in this quarterly report.

 

4. The registrant’s other certifying officer and I areresponsible for establishing and maintaining disclosure controls and procedures(as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrantand we have:

 

a)              Designed such disclosure controls and procedures, or causedsuch disclosure controls and procedures to be designed under our supervision,to ensure that material information relating to the registrant, including itsconsolidated subsidiaries, is made known to us by others within those entities,particularly during the period in which this quarterly report is beingprepared;

 

b)             Evaluated the effectiveness of the registrant’s disclosurecontrols and procedures****andpresented in this report our conclusions about the effectiveness of thedisclosure controls and procedures, as of the end of the period covered by thisreport based on such evaluation; and

 

c)              Disclosed in this report any change in the registrant’sinternal control over financial reporting that occurred during the registrant’smost recent fiscal quarter (the registrant’s fourth fiscal quarter in the caseof an annual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant’s internal control over financial reporting;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 registrant’s board of directors (or persons performing theequivalent function):

 

a)              All significant deficiencies and material weaknesses in thedesign or operation of internal control over financial reporting which arereasonably likely to adversely affect the registrant’s ability to record,process, summarize and report financial information;

 

b)             Any fraud, whether or not material, that involves managementor other employees who have a significant role in the registrant’s internalcontrols over financial reporting.

 

Date:  November 13,2003

 
|   |   |   |   |   |   |   |   |   |   |  /s/ John M. Fox    |   |
|--------|--------|--------|--------|--------|--------|--------|--------|--------|--------|--------------------------|--------|
|   |   |   |   |   |   |   |   |   |   |                     |
|   |   |   |   |   |   |   |   |   |   | John M. Fox              |
|   |   |   |   |   |   |   |   |   |   | Chief  Executive Officer |

 

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