|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |  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 |    |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   | 2007                        |    |   | 2006   |   |    | 2005   |   |   | 2004    |                         |   | 2003 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |
| Earnings      available to cover fixed charges:                                                                                                                                                                                                                                                                                                                                                         |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |
|        Net income                                                                                                                                                                                                                                                                                                                                                                                  |   |   | $                           | 66,277  |   |   | $      | 58,656  |   |   | $      | 53,476  |                         |   | $ | 62,106 |   |   | $ | 83,000 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
| Add:       Income tax expense                                                                                                                                                                                                                                                                                                                                                                      |   |   |                        | 34,197  |   |   |   | 27,814  |   |   |   | 26,128  |                         |   |   | 33,108 |   |   |   | 48,035 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|          Fixed charges                                                                                                                                                                                                                                                                                                                                                                   |   |   | 41,000                      |    |   |   | 45,041 |    |   |   | 43,203 |    |                         |   | 37,555 |   |   |   | 37,047 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|          Allowance for funds                                                                                                                                                                                                                                                                                                                                                             |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |
|             used during construction and other                                                                                                                                                                                                                                                                                                                            |   |   | (182                        | )       |   |   | (614   | )       |   |   | (1,038 | )       |                         |   | (363 | ) |   |   | (220 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   | $                           | 141,292 |   |   | $      | 130,897 |   |   | $      | 121,769 |                         |   | $ | 132,406 |   |   | $ | 167,862 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
| Fixed      charges:                                                                                                                                                                                                                                                                                                                                                                                     |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
| Interest      on debt                                                                                                                                                                                                                                                                                                                                                                                   |   | $      | 37,515                      |    |   | $      | 37,665 |    |   | $      | 36,487 |    |                         | $      | 35,606 |   |   | $ | 33,934 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
| Other      interest charges and                                                                                                                                                                                                                                                                                                                                                                         |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |
|   amortization      of debt discount,                                                                                                                                                                                                                                                                                                                                                         |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |
|   premium,      and expense, net                                                                                                                                                                                                                                                                                                                                                              |   |   | 3,485                       | *       |   |   | 7,376  |    |   |   | 6,716  |    |                         |   | 1,949 |   |   |   | 3,113 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   | $                           | 41,000  |   |   | $      | 45,041  |   |   | $      | 43,203  |                         |   | $ | 37,555 |   |   | $ | 37,047 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |   |   |                        |    |   |   |   |    |   |   |   |    |                         |   |   |   |   |   |   |   |   |
| Ratio      of earnings to fixed charges                                                                                                                                                                                                                                                                                                                                                                 |   |   | 3.45                        |    |   |   | 2.91   |    |   |   | 2.82   |    |                         |   | 3.53 |   |   |   | 4.53 |   |
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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. |   |