| **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 officers 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  officers and I have disclosed, based on 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 deficiencies**and  material weaknesses in 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 management or other employees who have a significant role in the  Company’s internal control over financial reporting.

Date: April 12, 2011

|        | By:    | /s/ Sebastián Eskenazi                                         |        |
|--------|--------|---------------------------------------------------------------------|--------|
|   |   |                                                                     |   |
|   |   | Name: Sebastián Eskenazi        Title: Chief Executive Officer |
|        |   |                                                                     |

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