UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 12b-25

NOTIFICATION OF LATE FILING

SEC File Number: 001-32647

CUSIP Number: 00208J108

(Check one)	¨  Form 10-K    ¨  Form 20-F    ¨  Form 11-K    x  Form 10-Q ¨  Form 10-D    ¨  Form N-SAR    ¨  Form N-CSR
	For Period Ended: September 30, 2012
	¨  Transition Report on Form 10-K
	¨  Transition Report on Form 20-F
	¨  Transition Report on Form 11-K
	¨  Transition Report on Form 10-Q
	¨  Transition Report on Form N-SAR
	For the Transition Period Ended:

Read Attached Instruction Sheet Before Preparing Form. Please Print or Type.

Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.

If the notification relates to a portion of the filing checked above, identify the item(s) to which the notification relates:

PART I—REGISTRANT INFORMATION

ATP OIL & GAS CORPORATION

Full Name of Registrant

Former Name if Applicable

4600 Post Oak Place, Suite 100

Address of Principal Executive Office (Street and Number)

Houston, Texas 77027

City, State and Zip Code

PART II—RULES 12b-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate.)

¨	(a	)	The reasons described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense;
	(b	)	The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, Form 11-K, Form N-SAR or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or subject distribution report on Form 10-D, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and
	(c	)	The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.

PART III—NARRATIVE

State below in reasonable detail the reasons why Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-SAR or N-CSR, or the transition report portion thereof, could not be filed within the prescribed time period. (Attach Extra Sheets if Needed.)

As previously disclosed, on August 17, 2012, ATP Oil & Gas Corporation (the “Company”) filed a voluntary petition for relief under Chapter 11 of Title 11 of the United States Bankruptcy Code in the United States Bankruptcy Court for the Southern District of Texas Case No. 12-36187. The Company has determined that it is unable to file its Quarterly Report on Form 10-Q for the quarter ended September 30, 2012 without unreasonable effort and expense due to the focus of the Company’s resources on the bankruptcy process. As a result, the Company’s financial results for the quarter ended September 30, 2012 have not been finalized. The Company intends to make such disclosures as are required in the bankruptcy process.

PART IV—OTHER INFORMATION

(1) Name and telephone number of person to contact in regard to this notification.

Albert L. Reese Jr.	(713)	622-3311
(Name)	(Area Code)	(Telephone Number)

(2) Have all other periodic reports required under Section 13 or 15(d) or the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months (or for such shorter period) that the registrant was required to file such report(s) been filed? If the answer is no, identify report(s).    ¨  Yes    x  No

Form 10-Q for the quarter ended June 30, 2012.

(3) Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof?     ¨  Yes    x  No

If so, attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made.

Due to the competing demands on Company management as a result of the bankruptcy process, the Company cannot reasonably estimate the results of operations for the quarter ended September 30, 2012.

ATP Oil & Gas Corporation

(Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned thereunto duly authorized.

Date: November 9, 2012	By:	/s/ Albert L. Reese Jr.
		Albert L. Reese Jr.
		Chief Financial Officer