UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q/A

(Amendment No. 1)

OR

Commission File Number: 001-34833

United States Commodity Index Funds Trust

(Exact name of registrant as specified in its charter)

1320 Harbor Bay Parkway, Suite 145

Alameda, California 94502

(Address of principal executive offices) (Zip code)

(510) 522-9600

(Registrant’s telephone number, including area code)

N/A

(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    x  Yes    ¨  No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    x  Yes    ¨  No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    ¨  Yes    x  No

Explanatory Note

The United States Commodity Index Funds Trust (the “Trust”) is filing this Amendment No. 1 to its quarterly report on Form 10-Q (“Form 10-Q/A”) for the quarter ended March 31, 2012 that was filed with the Securities and Exchange Commission on May 10, 2012 (“Form 10-Q”) in order to file amended principal executive officer and principal financial officer certifications originally filed as Exhibits 31.1 and 31.2 to the Form 10-Q, which inadvertently omitted certain language referring to internal control over financial reporting.

Except as set forth above, no other changes have been made to the Form 10-Q, and the Form 10-Q/A does not amend, update or change any other items or disclosure found in the Form 10-Q. Further, the Form 10-Q/A does not reflect events that occurred after the filing of the Form 10-Q.

Part II. OTHER INFORMATION

Listed below are the exhibits which are filed as part of this quarterly report on Form 10-Q/A (according to the number assigned to them in Item 601 of Regulation S-K):

(1)  Filed herewith.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

United States Commodity Index Funds Trust (Registrant)

By: United States Commodity Funds LLC, its Sponsor

Date: July 3, 2012

Date July 3, 2012