LIMITED LIABILITY COMPANY AGREEMENT OF CENTERPOINT ENERGY RESTORATION BOND COMPANY, LLC

Exhibit 3.6

LIMITED LIABILITY COMPANY AGREEMENT

OF

CENTERPOINT ENERGY RESTORATION BOND COMPANY, LLC

Effective as of September 28, 2009

TABLE OF CONTENTS

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LIMITED LIABILITY COMPANY AGREEMENT

This Limited Liability Company Agreement (this “Agreement”) is made and executed to be effective as of September 28, 2009, by CenterPoint Energy Houston Electric, LLC, a Texas limited liability company (“CenterPoint Houston”).

WHEREAS, a certificate of formation of CenterPoint Energy Restoration Bond Company, LLC (the “Company”), has been filed with the Secretary of State of the State of Delaware; and

WHEREAS, it is desired that the orderly management of the affairs of the Company be provided for;

ARTICLE I

DEFINITIONS

The following terms used in this Agreement shall have the following meanings (unless otherwise expressly provided herein):

“Agreement” shall mean this Agreement as originally executed and as it may be amended from time to time hereafter.

“Bonds” shall have the meaning given such term in Section 2.6.

“Capital Contribution” shall mean any contribution to the capital of the Company in cash or property by the Member whenever made.

“Certificate of Formation” shall mean the Certificate of Formation of the Company filed with and endorsed by the Secretary of State of the State of Delaware, as such certificate may be amended from time to time hereafter.

“Code” shall mean the Internal Revenue Code of 1986, as amended, or corresponding provisions of subsequent superseding federal revenue laws.

“Common Interest” shall have the meaning given such term in Section 4.1.

“Common Share” shall mean an undivided portion of all of the rights, duties, obligations and ownership interests in the Company.

“Delaware Act” shall mean the Delaware Limited Liability Company Act, as the same may be amended from time to time hereafter.

“Entity” shall mean any foreign or domestic general partnership, limited partnership, limited liability company, corporation, joint enterprise, trust, business trust, employee benefit plan, cooperative or association.

“Financing Order” shall mean and include the financing order issued by the PUCT on August 26, 2009 in Docket No. 37200 and any subsequent financing order issued by the PUCT to the Member pursuant to which the Member transfers its rights and interests thereunder to the Company in connection with the issuance of a separate series of Bonds.

“Fiscal Year” shall mean the Company’s fiscal year, which shall be determined by the Managers in accordance with Section 706(b) of the Code.

“Governmental Authority” shall mean any court or any federal or state regulatory body, administrative agency or governmental instrumentality.

“Manager” shall mean any of the managers of the Company duly appointed or elected to serve in such capacity under Delaware law and this Agreement.

“Member” shall mean each Person who executes a counterpart of this Agreement as a Member and each Person who may hereafter become a Member pursuant to Article XII; but shall not include any Member that ceases to be a Member.

“Person” shall mean any individual or Entity, and any heir, executor, administrator, legal representative, successor or assign of such “Person” where the context so admits.

“Public Utility Regulatory Act” means the Texas Public Utility Regulatory Act, as codified in Title II of the Texas Utilities Code.

“PUCT” shall mean the Public Utility Commission of Texas or any successor entity thereto.

“System Restoration Property” shall mean the rights and interests of CenterPoint Houston or its successor under a Financing Order, once those rights are first transferred to the Company or pledged in connection with the issuance of the related series of Bonds, including the right to impose, collect and receive through system restoration charges payable by retail electric customers within CenterPoint Houston’s certificated service area as it existed on the date of such Financing Order, an amount sufficient to cover the qualified costs of CenterPoint Houston authorized in such Financing Order, the right to receive system restoration charges in amounts and at times sufficient to pay principal and interest and make other deposits in connection with such related series of Bonds and all revenues and collections resulting from system restoration charges. System Restoration Property is known as “transition property” the Public Utility Regulatory Act.

“Treasury Regulations” shall mean regulations, including proposed or temporary regulations, promulgated under the Code. References herein to specific provisions of proposed or temporary regulations shall include analogous provisions of final Treasury Regulations or other successor Treasury Regulations.

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ARTICLE II

FORMATION OF THE COMPANY

2.1 Formation . On August 6, 2009, the Certificate of Formation of the Company was filed with the Secretary of State of the State of Delaware pursuant to the Delaware Act.

2.2 Name . The name of the Company is CenterPoint Energy Restoration Bond Company, LLC. If the Company shall conduct business in any jurisdiction other than the State of Delaware, it shall register the Company or its trade name with the appropriate authorities in such state in order to have the legal existence of the Company recognized.

2.3 Place of Business . The Company may locate its places of business and registered office at any place or places as the Managers may from time to time deem advisable.

2.4 Registered Office and Registered Agent . The Company’s registered office shall be at the office of its registered agent at 1209 Orange Street, Wilmington, Delaware 19801, and the name of its initial registered agent at such address shall be The Corporation Trust Company.

2.5 Term . The Company and this Agreement shall continue until the earliest of (a) such time as all of the Company’s assets have been sold or otherwise disposed of or (b) such time as the Company’s existence has been terminated as otherwise provided herein or in the Delaware Act.

2.6 Business Purpose . The nature of the business or purpose to be conducted or promoted by the Company is to engage exclusively in the following business and financial activities:

(a) to authorize, issue, sell and deliver one or more series or classes of system restoration bonds (as defined in the Public Utility Regulatory Act) (the “Bonds”) and, in connection therewith, to enter into any agreement or document providing for the authorization, issuance, sale and delivery of the Bonds;

(b) to purchase, acquire, own, hold, administer, service, and enter into agreements for the servicing of, finance, manage, sell, assign, pledge, collect amounts due on and otherwise deal with the System Restoration Property and other assets to be acquired in connection therewith and any proceeds or rights associated therewith;

(c) to negotiate, authorize, execute, deliver, assume the obligations under, and perform its duties under, any agreement, instrument or document relating to the activities set forth in clauses (a) and (b) above; provided, that each party to any such agreement under which material obligations are imposed upon the Company shall covenant that it shall not, prior to the date which is one year and one day after the termination of the indenture providing for the Bonds and the payment in full of each series of Bonds and any other amounts owed under such indenture, acquiesce, petition or otherwise invoke or cause the Company to invoke the process of any court or Governmental Authority for the purpose of commencing or sustaining a

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case against the Company under any federal or state bankruptcy, insolvency or similar law or appointing a receiver, liquidator, assignee, trustee, custodian, sequestrator or other similar official of the Company or any substantial part of the property of the Company; or ordering the winding up or liquidation of the affairs of the Company; and provided, further, that the Company shall be permitted to incur additional indebtedness or other liabilities payable to service providers and trade creditors in the ordinary course of business in connection with the foregoing activities;

(d) to invest proceeds from the System Restoration Property and its other assets and any capital and income of the Company in accordance with the applicable agreements or instruments entered into in connection with the issuance of the Bonds or as otherwise determined by the Managers and not inconsistent with this Section or such applicable agreements or instruments;

(e) to do such other things and carry on any other activities which the Managers determine to be necessary, convenient or incidental to any of the foregoing purposes, and have and exercise all of the powers and rights conferred upon limited liability companies formed pursuant to the Delaware Act that are related or incidental to any of the foregoing; and

(f) to enter into and perform all agreements or instruments entered into in connection with the issuance of the Bonds and all documents, certificates or financing statements contemplated thereby or related thereto, all without any further act, vote or approval of the Member, any Manager or other Person notwithstanding any other provision of this Agreement, the Delaware Act or applicable law, rule or regulation. The foregoing authorization shall not be deemed a restriction on the powers of the Member or any Manager to enter into other agreements on behalf of the Company.

ARTICLE III

INITIAL MEMBER

The name and place of business of the initial Member are as follows:

CenterPoint Energy Houston Electric, LLC

1111 Louisiana

Houston, Texas 77002

ARTICLE IV

CAPITAL OF THE COMPANY

4.1 Common Shares and Initial Contributions .

(a) A class of equity interests denominated the “Common Shares” is hereby designated as the sole class of equity interests of the Company. Each issued and outstanding Common Share shall at any time represent that undivided portion of all of the rights, duties, obligations and ownership interests in the Company in proportion to the total number of Common Shares outstanding at such time.

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(b) The Company will issue to the initial Member 1,000 Common Shares (together, the “Common Interest”) upon payment of $1,000 to the Company from the Initial Member, which shall be deemed to be the initial Capital Contribution of the initial Member. Upon receipt of such initial Capital Contribution and execution of this Agreement by the Member, such Common Shares shall be validly issued and outstanding, fully paid and nonassessable.

4.2 Additional Contributions . The Member shall not be required to make additional Capital Contributions unless, and except on such terms as, the Managers and the Member unanimously agree.

4.3 Interest . No interest shall be paid by the Company on Capital Contributions.

ARTICLE V

RIGHTS AND OBLIGATIONS OF THE MEMBER

5.1 Limitation of Member’s Responsibility, Liability . The Member shall not perform any act on behalf of the Company, incur any expense, obligation or indebtedness of any nature on behalf of the Company, or in any manner participate in the management of the Company or receive or be credited with any amounts, except as specifically contemplated hereunder. The Member shall not be personally liable for any amount in excess of its Capital Contribution, and shall not be liable for any of the debts or losses of the Company, except to the extent that a liability of the Company is founded upon or results from an unauthorized act or activity of the Member. In addition, the Member’s liability shall be limited as set forth in the Delaware Act and other applicable law hereafter in effect.

5.2 Return of Distributions . In accordance with Section 18-607 of the Delaware Act, the Member will be obligated to return any distribution from the Company only as provided by applicable law.

ARTICLE VI

ACTS OF THE MEMBER

6.1 Action by the Member With a Meeting . The Member may act by voting the Common Interest at a meeting, which may be called by the Member or any Manager, and which may b