| |  |            
| |  | -----------
| |  | Exhibit 7.1
| |  | (1 of 2)   



PETROLEOS MEXICANOS,
SUBSIDIARY ENTITIES AND SUBSIDIARY COMPANIES



Computation
of ratio of earnings to fixed charges

(Thousand of constant pesos as of December 31, 2004)



|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|------------------------------------------------------------------------------- |  | -------------- | - |  | -------------- | - |  | -------------- | - |  | -------------- | -
|                                                                                |  | 2004           |   |  | 2003           |   |  | 2002           |   |  | 2001           |  
|Mexican GAAP                                                                    |  |                |   |  |                |   |  |                |   |  |                |  
|Fixed Charges(1):                                                               |  |                |   |  |                |   |  |                |   |  |                |  
|Interest capitalized in fixed assets                                            |  | Ps. 4,339,933  |   |  | Ps. 7,622,449  |   |  | Ps. 5,752,053  |   |  | Ps. 4,369,475  |  
|Interest in the specific reserve for exploration and depletion                  |  | 0              |   |  | 20,029         |   |  | 52,638         |   |  | 100,063        |  
|Interest expense                                                                |  | 31,764,579     |   |  | 24,706,311     |   |  | 22,059,995     |   |  | 18,707,235     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Total interest cost                                                             |  | 36,104,512     |   |  | 32,348,789     |   |  | 27,864,686     |   |  | 23,176,773     |  
|Total Fixed Charges                                                             |  | 36,104,512     |   |  | 32,348,789     |   |  | 27,864,686     |   |  | 23,176,773     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Earnings after IEPS taxes and Hydrocarbon Extraction duties                     |  | (25,495,610    | ) |  | (42,754,131    | ) |  | (25,849,641    | ) |  | (31,973,453    | )
|Fixed Charges(1):                                                               |  |                |   |  |                |   |  |                |   |  |                |  
|Interest cost (net of amounts capitalized)                                      |  | 31,764,579     |   |  | 24,706,311     |   |  | 22,059,995     |   |  | 18,707,235     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Total Fixed Charges (net of amounts capitalized)                                |  | 31,764,579     |   |  | 24,706,311     |   |  | 22,059,995     |   |  | 18,707,235     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Earnings after taxes and duties plus fixed charges (net of amounts capitalized) |  | 6,268,969      |   |  | (18,047,820    | ) |  | (3,789,646     | ) |  | (13,266,217    | )
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Amount by which fixed charges exceed earnings                                   |  | Ps. 29,835,543 |   |  | Ps. 50,396,609 |   |  | Ps. 31,654,332 |   |  | Ps. 36,442,991 |  

---

|(1) | These figures do not include rental expense
|--- | -------------------------------------------



---

| |  |            
| |  | -----------
| |  | Exhibit 7.1
| |  | (2 of 2)   



PETROLEOS MEXICANOS
SUBSIDIARY ENTITIES AND SUBSIDIARY COMPANIES



Computation
of ratio of earnings to fixed charges

(Thousand of constant pesos as of December 31, 2004)



|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|------------------------------------------------------------------------------- |  | -------------- | - |  | -------------- | - |  | -------------- | - |  | -------------- | -
|                                                                                |  | 2004           |   |  | 2003           |   |  | 2002           |   |  | 2001           |  
|U.S. GAAP                                                                       |  |                |   |  |                |   |  |                |   |  |                |  
|Fixed Charges(1):                                                               |  |                |   |  |                |   |  |                |   |  |                |  
|Interest capitalized in fixed assets                                            |  | Ps. 5,228,236  |   |  | Ps. 8,367,505  |   |  | Ps. 6,311,633  |   |  | Ps. 6,010,456  |  
|Interest expense                                                                |  | 30,876,276     |   |  | 23,981,284     |   |  | 21,553,053     |   |  | 17,166,318     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Total interest cost                                                             |  | 36,104,512     |   |  | 32,348,789     |   |  | 27,864,686     |   |  | 23,176,773     |  
|Total Fixed Charges                                                             |  | 36,104,512     |   |  | 32,348,789     |   |  | 27,864,686     |   |  | 23,176,773     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Income Earnings after taxes and duties                                          |  | (13,011,182    | ) |  | (69,751,377    | ) |  | (34,362,362    | ) |  | (24,556,132    | )
|Fixed Charges(1):                                                               |  |                |   |  |                |   |  |                |   |  |                |  
|Interest cost (net of amounts capitalized)                                      |  | 30,876,276     |   |  | 23,981,284     |   |  | 21,553,053     |   |  | 17,166,318     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Total Fixed Charges (net of amounts capitalized)                                |  | 30,876,276     |   |  | 23,981,284     |   |  | 21,553,053     |   |  | 17,166,318     |  
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Earnings after taxes and duties plus fixed charges (net of amounts capitalized) |  | 17,865,094     |   |  | (45,770,093    | ) |  | (12,809,309    | ) |  | (7,389,815     | )
|                                                                                |  |                |   |  |                |   |  |                |   |  |                |  
|Amount by which fixed charges exceed earnings                                   |  | Ps. 18,239,418 |   |  | Ps. 78,118,882 |   |  | Ps. 40,673,995 |   |  | Ps. 30,566,588 |  

---

|(1) | These figures do not include rental expense
|--- | -------------------------------------------