|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |  Nicor      Gas Company |
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|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |  Form      10-K         |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |  Exhibit      12.01     |
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| Nicor      Gas Company                                                                                                                                                                                                                                                                                                                                                                       |
| Computation      of Consolidated Ratio of Earnings to Fixed Charges                                                                                                                                                                                                                                                                                                                          |
| (thousands)                                                                                                                                                                                                                                                                                                                                                                                  |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   | Year      Ended December 31 |        |
|                                                                                                                                                                                                                                                                                                                                                                                         |   | 2008                        |        |   | 2007   |   |    | 2006   |   |                         | 2005 |   |   | 2004 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
| Earnings      available to cover fixed charges:                                                                                                                                                                                                                                                                                                                                              |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |
| Net      income                                                                                                                                                                                                                                                                                                                                                                              |   | $                           | 59,569      |   |   | $      | 66,277  |   |   | $                            | 58,656 |   |   | $ | 53,476 |   |   | $ | 62,106 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|         Add:  Income      tax expense                                                                                                                                                                                                                                                                                                                                         |   |                        | 30,991      |   |   |   | 34,197  |   |   |                         | 27,814 |   |   |   | 26,128 |   |   |   | 33,108 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|  Fixed      charges                                                                                                                                                                                                                                                                                                                                                                     |   |                        | 38,246      |   |   |   | 41,000  |   |   |                         | 45,041 |   |   |   | 43,203 |   |   |   | 37,555 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|  Allowance      for funds                                                                                                                                                                                                                                                                                                                                                               |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|          used during construction and other                                                                                                                                                                                                                                                                                                                                   |   |                        | (62         | )      |   |   | (182    | )      |   |                         | (614 | ) |   |   | (1,038 | ) |   |   | (363 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   | $                           | 128,744     |   |   | $      | 141,292 |   |   | $                            | 130,897 |   |   | $ | 121,769 |   |   | $ | 132,406 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
| Fixed      charges:                                                                                                                                                                                                                                                                                                                                                                          |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
| Interest      on debt                                                                                                                                                                                                                                                                                                                                                                        |   | $                           | 35,204      |   |   | $      | 37,515  |   |   | $                            | 37,665 |   |   | $ | 36,487 |   |   | $ | 35,606 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
| Other      interest charges and                                                                                                                                                                                                                                                                                                                                                              |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|   amortization      of debt discount,                                                                                                                                                                                                                                                                                                                                              |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|   premium,      and expense, net                                                                                                                                                                                                                                                                                                                                                   |   |                        | 3,042  | *      |   |   | 3,485   | *      |   |                         | 7,376 |   |   |   | 6,716 |   |   |   | 1,949 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   | $                           | 38,246      |   |   | $      | 41,000  |   |   | $                            | 45,041 |   |   | $ | 43,203 |   |   | $ | 37,555 |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                         |   |                        |        |   |   |   |    |   |   |                         |   |   |   |   |   |   |   |   |   |   |
| Ratio      of earnings to fixed charges                                                                                                                                                                                                                                                                                                                                                      |   |                        | 3.37        |   |   |   | 3.45    |   |   |                         | 2.91 |   |   |   | 2.82 |   |   |   | 3.53 |   |
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| *        The Company adopted FIN No. 48 on January 1, 2007. Accordingly, for      2007 and going forward, the interest included in Fixed charges is only the      interest on third party indebtedness. Any interest expense accrued on      uncertain tax positions is excluded from the calculation of      Earnings. Prior years' calculations were not changed. |   |