|        |
|--------|
|        |
|   |

|   |
|---|
|   |  |
| x | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

|        |
|--------|
|        |  |
| ¨ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

|                                                                |
|----------------------------------------------------------------|
|                                                                |  |  |
| New Mexico                                                     |   | 75-0575400 |
| (State or other jurisdiction of incorporation or organization) |   | (I.R.S. Employer Identification No.) |
|                                                           |   |   |
| Tyler at Sixth                                                 |   |   |
| Amarillo, Texas                                                |   | 79101 |
| (Address of principal executive offices)                       |   | (Zip Code) |

|                                             |
|---------------------------------------------|
|                                             |  |  |
| Large accelerated filer ¨              |   | Accelerated filer ¨ |
| Non-accelerated filer x                     |   | Smaller reporting company ¨ |
| (Do not check if smaller reporting company) |   |   |

|                            |
|----------------------------|
|                            |  |  |
| Class                      |   | Outstanding at Oct. 28, 2013 |
| Common Stock, $1 par value |   | 100 shares |

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|--------|
|        |
|   |

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|    |
|----|
|    |  |
| *  | Indicates incorporation by reference |
| #  | This exhibit is filed or furnished herewith |
| ## | This exhibit has been previously filed or furnished |

|         |
|---------|
|         |  |
| ##3.01* | Amended and Restated Articles of Incorporation of SPS dated Sept. 30, 1997 (Exhibit 3(a)(2) to Form 10-K (file no. 001-03789) dated March 3, 1998). |
| #3.02   | By-Laws of SPS as Amended and Restated on Sept. 26, 2013. |
| #31.01  | Principal Executive Officer’s certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |
| #31.02  | Principal Financial Officer’s certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |
| ##32.01 | Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. |
| ##99.01 | Statement pursuant to Private Securities Litigation Reform Act of 1995. |
| ##101   | The following materials from SPS’ Quarterly Report on Form 10-Q for the quarter ended Sept. 30, 2013 are formatted in XBRL (eXtensible Business Reporting Language):  (i) the Statements of Income, (ii) the Statements of Comprehensive Income (iii) the Statements of Cash Flows, (iv) the Balance Sheets, (v) Notes to Condensed Financial Statements, and (vi) document and entity information. |

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|              |
|--------------|
|              |  |  |
|         |   | Southwestern Public Service Company |
|         |   |   |
| Nov. 8, 2013 | By: | /s/ JEFFREY S. SAVAGE |
|         |   | Jeffrey S. Savage |
|         |   | Vice President and Controller |
|         |   |   |
|         |   | /s/ TERESA S. MADDEN |
|         |   | Teresa S. Madden |
|         |   | Senior Vice President, Chief Financial Officer and Director |