Exhibit
12.1




CERTIFICATION






I,
Sebastián Eskenazi, certify that:




1.           I
have reviewed this annual report on Form 20-F of YPF Sociedad Anónima (the
“Company”);




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




3.           Based
on my knowledge, the financial statements, and other financial information
included in this report, fairly present in all material respects the financial
condition, results of operations and cash flows of the Company as of, and for,
the periods presented in this report;




4.           The
Company’s other certifying officer and I are responsible for establishing and
maintaining disclosure controls and procedures (as defined in Exchange Act Rules
13a-15(e) and 15d-15(e)) and internal control over financial reporting (as
defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the Company and
have:




(a)           Designed
such disclosure controls and procedures, or caused such disclosure controls and
procedures to be designed under our supervision, to ensure that material
information relating to the Company, including its consolidated subsidiaries, is
made known to us by others within those entities, particularly during the period
in which this report is being prepared;




(b)           Designed
such internal control over financial reporting, or caused such internal control
over financial reporting to be designed under our supervision, to provide
reasonable assurance regarding the reliability of financial reporting and the
preparation of financial statements for external purposes in accordance with
generally accepted accounting principles;




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




(d)           Disclosed
in this report any change in the Company’s internal control over financial
reporting that occurred during the period covered by the annual report that has
materially affected, or is reasonably likely to materially affect, the Company’s
internal control over financial reporting; and












5.           The
Company’s other certifying officer and I have disclosed, basedon our most recent evaluation of internal control over financial
reporting, to the Company’s auditors and the audit committee of the Company’s
board of directors (or persons performing the equivalent
functions):




(a)           All
significant deficienciesandmaterial
weaknessesin the design or operation of internal control over financial
reporting which are reasonably likely to adversely affect the Company’s ability
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
Company’s internal control over financial reporting.







Date:
October 17, 2008





By:
            /s/Sebastián
      EskenaziName:
            Sebastián
      EskenaziTitle:
            Chief
      Executive Officer