**Exhibit 31.2**

 

**CERTIFICATION**

 

I, James G. Ivey certifythat:

 

1. I have reviewed thisquarterly report on Form 10-Q of MarkWest Hydrocarbon, Inc.;

 

2. Based on myknowledge, this report does not contain any untrue statement of a material factor omit to state a material fact necessary to make the statements made, inlight of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report;

 

3. Based on myknowledge, the financial statements, and other financial information includedin this report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, andfor, the periods presented in this report;

 

4. The registrant’sother certifying officers and I are responsible for establishing andmaintaining disclosure controls and procedures (as defined in Exchange ActRules 13a-15(e) and 15d-15(e)) and internal control over financialreporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f))for the registrant and have:

 

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 overfinancial reporting, or caused such internal control over financial reportingto be designed under our supervision, to provide reasonable assurance regardingthe reliability of financial reporting and the preparation of financialstatements for external purposes in accordance with generally acceptedaccounting principles;

 

c)              Evaluated the effectiveness of theregistrant’s disclosure controls and procedures****and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end of theperiod covered by this report based on such evaluation; and

 

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’sother certifying officers and I have disclosed, based on our most recentevaluation of internal control over financial reporting, to the registrant’sauditors and the audit committee of the registrant’s board of directors (orpersons performing the equivalent function):

 

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, that involves managementor other employees who have a significant role in the registrant’s internalcontrols over financial reporting.

 

 
| Date:  May 8, 2006 | By:    |   | /s/ JAMES G. IVEY                                  |
|------------------------------|--------|--------|----------------------------------------------------|
|                         |   |   | James G. Ivey                                      |
|                         |   |   | Senior Vice President and Chief Financial  Officer |

 

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