SENIOR SECURED CONVERTIBLE PROMISSORY NOTE

Exhibit 10.10

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”) OR ANY APPLICABLE STATE SECURITIES LAWS, AND MAY NOT BE SOLD, TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS THERE IS AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT OR ANY APPLICABLE STATE SECURITIES LAWS COVERING SUCH SECURITIES OR THE SALE IS MADE IN ACCORDANCE WITH AN EXEMPTION UNDER THE SECURITIES ACT AND ANY APPLICABLE STATE SECURITIES LAWS, AND THE COMPANY RECEIVES AN OPINION OF COUNSEL FOR THE HOLDER OF THESE SECURITIES REASONABLY SATISFACTORY TO THE COMPANY STATING THAT SUCH SALE, TRANSFER, ASSIGNMENT OR HYPOTHECATION IS EXEMPT FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT AND ANY APPLICABLE STATE SECURITIES LAWS.

SENIOR SECURED CONVERTIBLE PROMISSORY NOTE

FOR VALUE RECEIVED , the undersigned, TRX, Inc. , a Georgia corporation (the “Company”), promises to pay to the order of Sabre Investments, Inc. (the “Holder”) at the offices of Holder located at 3150 Sabre Drive, Southlake, Texas 76092-2129, or at such other place as the Holder may designate in writing to the undersigned, in lawful money of the United States of America, and in immediately available funds, the principal sum of FIFTEEN MILLION DOLLARS ($15,000,000.00) (the “Principal Amount”), together with interest on the principal sum hereof from time to time outstanding hereunder (computed on the basis of a 360-day year for the actual number of days elapsed) from the date hereof until paid in full at a per annum rate equal to seven percent (7%).

1.1 This Note is the Note referred to in that certain Senior Secured Convertible Note Purchase Agreement, dated as of the date hereof, by and between the Company and Holder (the “Note Purchase Agreement”).

1.2 The principal balance shall be payable on November 30, 2006 (“Maturity Date”), subject to the right of the Holder to demand earlier payment of a portion of such principal balance upon the conditions set forth in Exhibit A attached hereto and incorporated herein. The principal balance under this Note shall not be repaid prior to the Maturity Date without the prior written consent of the Holder.

1.3 Interest will be paid semi-annually, in arrears, with the first installment of interest due on May 30, 2002 and each subsequent interest payment due on six month anniversary of such date (unless such date is not a business day in which case the payment is due on the next succeeding business day) and on any other date on which the principal balance is due (whether by acceleration, maturity or otherwise) until the principal amount of this Note is paid in full.

1.4 Interest shall accrue on any amount past due hereunder at a rate equal to three percent (3%) per annum in excess of the interest rate otherwise payable hereunder. All such interest shall be due and payable on demand.

1.5 In no event shall the amount of interest due or payable under this Note exceed the maximum rate of interest allowed by applicable law and, in the event any such payment is inadvertently paid by the undersigned or inadvertently received by the Holder, then such excess sum shall be credited as a payment of principal, unless the undersigned shall notify the Holder in writing that the undersigned elects to have such excess sum returned to it forthwith. It is the express intent of the parties hereto that the

undersigned not pay and the Holder not receive, directly or indirectly, in any manner whatsoever, interest in excess of that which may be lawfully paid by the undersigned under applicable law.

1.6 THE COMPANY, AND THE HOLDER BY ACCEPTING THIS NOTE, EACH AGREE AND STIPULATE THAT THE ONLY CHARGE IMPOSED UPON THE UNDERSIGNED FOR THE USE OF MONEY IN CONNECTION WITH THIS NOTE IS AND SHALL BE THE INTEREST DESCRIBED IN THE FIRST PARAGRAPH HEREOF, AND FURTHER AGREE AND STIPULATE THAT ALL OTHER CHARGES IMPOSED BY THE HOLDER ON THE COMPANY IN CONNECTION WITH THIS NOTE, ALL DEFAULT CHARGES, LATE CHARGES, AND REASONABLE ATTORNEYS’ FEES, ARE CHARGES MADE TO COMPENSATE THE HOLDERS FOR UNDERWRITING OR ADMINISTRATIVE SERVICES AND COSTS OR LOSSES PERFORMED OR INCURRED, AND TO BE PERFORMED OR INCURRED, BY THE HOLDER IN CONNECTION WITH THIS NOTE AND SHALL UNDER NO CIRCUMSTANCES BE DEEMED TO BE CHARGES FOR THE USE OF MONEY PURSUANT TO OFFICIAL CODE OF GEORGIA ANNOTATED SECTION 7-4-2 OR SECTION 7-4-18. ALL CHARGES OTHER THAN CHARGES FOR THE USE OF MONEY SHALL BE FULLY EARNED AND NONREFUNDABLE WHEN DUE.

2.1 Subject to the provisions of this Section, at the option of the Holder, all of the outstanding principal amount plus any accrued and due but unpaid interest under this Note may be converted, in whole, at any time on or before the Maturity Date, into shares of the Company’s common stock, $.01 par value per share (the “Common Stock”), at the Conversion Price, determined as provided below, provided, however , if prior to such conversion the Company shall issue any other class or series of capital stock (the “Senior Stock”), Holder, at its option, may elect to convert all of the outstanding principal amount plus any accrued and due but unpaid interest under this Note into shares of the Senior Stock on the terms and conditions as set forth herein.

2.2 Upon conversion of this Note, the Holder shall be entitled to receive one share of Common Stock for each eleven dollars and three cents ($11.03) of principal and accrued and due but unpaid interest through the Conversion Date (“Conversion Price”). As payment of accrued and unpaid but not yet due interest, at the election of the Company the Holder shall be entitled to receive either (a) a number of shares of Common Stock equal to such amount of interest divided by the Conversion Price, or (b) a cash amount equal to such amount of interest. No fractional shares of Common Stock shall be issued upon the conversion of this Note. Instead of a fraction of a share of Common Stock which would otherwise be issuable upon conversion of this Note, the Company shall pay a cash adjustment in respect of such fraction of a share of Common Stock in an amount equal to the same fractional interest of the Conversion Price. The Company shall pay all taxes and other charges in respect of the issuance of shares of Common Stock to the Holder upon such conversion.

2.3 In the case that the Company shall, after the date hereof, issue or enter into an agreement to issue additional shares of Common Stock, or securities convertible into Common Stock (except for (i) shares of capital stock issued upon conversion of any shares of the Company’s preferred stock, (ii) shares of capital stock issued or issuable pursuant to options, or purchase agreements, warrants, capital appreciation rights, calls, convertible shares, convertible debt securities or other rights to acquire the Company’s authorized and unissued capital stock which are outstanding on the date hereof, (iii) shares issued pursuant to options granted under the Company’s option plan after the date hereof so long as the exercise price of such options is greater than $5.51, (iv) shares of Common Stock issued pursuant to a subdivision of the Common Stock or stock dividend pursuant to which the number of shares for which this Note is convertible and the purchase price therefore are adjusted pursuant to Section 2.7 hereof, or (v) shares of capital stock issued pursuant to the exchange, conversion or exercise of any securities

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convertible into Common Stock that have previously been incorporated into computations hereunder) at a purchase price per share for which Common Stock is issuable is less than the Conversion Price then in effect (the “ Dilutive Purchase Price ”), the Conversion Price then in effect shall become the Dilutive Purchase Price. Promptly after any adjustment in the Conversion Price pursuant to this Section 2.3, the Company shall give written notice to the Holder of the Conversion Price following such adjustment, together with a schedule of computations of such adjustment.

2.4 In order to exercise the right of conversion pursuant to Section 2.1 above, the Holder shall give written notice to the Company that the Holder has elected to convert this Note. Following receipt of such conversion notice, the Holder shall surrender this Note to the Company at its principal office. Upon receipt of the Note so surrendered by the Holder, the Company shall issue and deliver to the Holder the certificate or certificates or other document evidencing the shares of Common Stock issuable on such conversion. Such conversion shall be deemed to have been effected at the close of business on the date of surrender of the Note to the Company (the “Conversion Date”) and at such time all rights of the Holder under this Note shall cease and the Holder shall be deemed to have become a holder of record of the shares of Common Stock of the Company into which this Note was converted.

2.5 On the Conversion Date, the Secretary of the Company shall deliver to the Holder a certificate executed by the Secretary, dated as of the Conversion Date, certifying that the representations and warranties contained in Section 3 of the Note Purchase Agreement are true and correct in all material respects as of the Conversion Date.

2.6 In the event of any taking by the Company of a record of the holders of any class of securities for the purpose of determining the holders thereof who are entitled to receive any dividend or other distribution or any right to subscribe for, purchase or otherwise acquire any shares of stock of any class or any other securities or property, or to receive any other right, the Company shall mail to the Holder, at least twenty (20) days prior to the date specified therein, a notice specifying the date on which any such record is to be taken for the purpose of such dividend, distribution or rights, and the amount and character of such dividend, distribution or rights.

2.7 Anti-Dilution Adjustments .

(a) If the Company shall at any time subdivide the outstanding shares of Common Stock or effect a forward stock split by issuing stock dividends, then the number of shares of Common Stock for which this Note is convertible immediately prior to that subdivision (the “Number of Note Shares”) shall be proportionately increased and the purchase price therefor proportionately decreased, and if the Company shall at any time combine the outstanding shares of Common Stock, then the Number of Note Shares shall be proportionately decreased and the purchase price therefor proportionately increased. Any adjustment under this Section 2 shall become effective at the close of business on the date the subdivision or combination becomes effective.

(b) If the Common Stock issuable on conversion of this Note shall be changed into the same or a different number of shares of any other class or classes of stock, whether by capital reorganization, reclassification, or otherwise (other than a subdivision or combination of shares provided for above), then the Holder of this Note shall, upon its conversion, be entitled to receive, in lieu of the Common Stock which the Holder would have become entitled to receive but for such change, that number of shares of such other class or classes of stock which is equivalent to the number of shares of Common Stock that would have been subject to receipt by the Holder on conversion of this Note immediately prior to that change.

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(c) If at any time there shall be a capital reorganization of the Company’s Common Stock (other than a subdivision, combination, reclassification or exchange of shares provided for elsewhere in this Note) or merger or consolidation of the Company with or into another corporation, or the sale of the Company’s properties and assets as, or substantially as, an entirety to any other person or association, then as a part of such reorganization, merger, consolidation or sale, lawful provision shall be made so that the Holder of this Note shall thereafter be entitled to receive upon conversion of this Note, the number of shares of stock or other securities or property of the Company, or of the successor corporation or other person resulting from such merger or consolidation, to which a Holder of the Common Stock deliverable upon conversion of this Note would have been entitled on such capital reorganization, merger, consolidation, or sale if this Note had been converted immediately prior to that reorganization, merger, consolidation, or sale. In any such case, appropriate adjustment shall be made in the application of the provisions of this Note with respect to the rights of the Holder after the reorganization, merger, consolidation, or sale to the end that the provisions of this Note (including adjustment of the Number of Note Shares then in effect) shall be applicable after that event in a manner as nearly equivalent as may be practicable.

3.1 The unpaid principal of and interest on this Note and all other obligations of the Company of any kind whatsoever under or in respect of this Note (the “Senior Obligations”) are hereby expressly senior and preferred in right of payment to all indebtedness and securities of the Company or guaranteed by the Company now or hereafter arising and the Company shall not incur or guarantee any indebtedness unless such instruments representing such indebtedness expressly subordinates such indebtedness to the Senior Obligations.

3.2 Notwithstanding the foregoing Section 3.1 or anything else set forth in this Note, the Holder acknowledges and agrees that, if the Company’s pre-tax Fixed Charge Ratio (as defined below) is 1.5 or greater prior to closing of a credit facility for working capital (the “Working Capital Facility”), and the Company’s Maximum Leverage Ratio (as defined below) is 3.0 or less prior to closing of a Working Capital Facility, then Holder shall not unreasonably withhold or delay consent for the Company to enter into such Working Capital Facility with any other lender (the “Working Capital Lender”) in an amount not to exceed the lesser of (a) 85% of eligible accounts receivable or (b) $5,000,000 and to be secured by a first priority security interest in the accounts receivable of the Company and its subsidiaries and that, in connection with any such Working Capital Facility, the Working Capital Lender may be granted a senior security and superior interest in the Company’s and its subsidiaries’ accounts receivables to the security interest in such accounts receivable granted to the Holder pursuant to the Security Agreement and the Subsidiary Security Agreement; provided, however, that if the Company’s pre-tax Fixed Charge Ratio and Maximum Leverage Ratio is not maintained as provided in this section subsequent to Holder’s consent, then the Company’s balance on the Working Capital Facility must be maintained at zero until such time as the ratios are again achieved. The Company will provide to Holder a quarterly calculation of the pre-tax Fixed Charge Ratio and the Maximum Leverage Ratio within 30 days of the close of each quarter if the balance of the Working Capital Facility is greater than zero. In no event shall the Company be permitted to enter into such Working Capital Facility without the consent of the Holder.

As used herein Fixed Charge Ratio means a ratio for which the numerator shall be pretax income from continuing operations plus interest expense plus gross rents and the denominator shall be gross interest expense plus gross rents. Pretax income from continuing operations for purposes of determining the Fixed Charge Ratio, as of any date for the trailing twelve month period ending on such date with respect to the Company on a consolidated basis, shall mean pretax income from continuing operations as determined in accordance with GAAP (as defined below). Interest expense for purposes of determining the Fixed Charge Ratio, as of any date for the trailing twelve month period ending on such date with respect to the Company on a consolidated basis, shall mean interest expense as determined in accordance with GAAP.

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Gross rents for purposes of determining the Fixed Charge Ratio, as of any date for the trailing twelve month period ending on such date with respect to the Company on a consolidated basis, shall mean gross operating rent expense before subtracting sublease income as determined in accordance with GAAP.

Gross interest expense for purposes of determining the Fixed Charge Ratio, as of any date for the trailing twelve month period ending on such date with respect to the Company on a consolidated basis, shall mean interest expense before subtracting capitalized interest as determined in accordance with GAAP less non-cash interest expense associated with the warrants issued pursuant to this Agreement. Determination of gross interest expense would not be netted against interest income.

As used herein Maximum Leverage Ratio means a ratio for which the numerator shall be total funded debt and the denominator shall be EBITDA. Total funded debt for purposes of determining the Maximum Leverage Ratio shall mean, (a) all obligations for borrowed money, (b) all obligations evidenced by bonds, debentures, notes or similar instruments, (c) all obligations under conditional sale or other title retention agreements relating to property purchased (other than customary reservations or retentions of title under agreements with suppliers entered into in the ordinary course of business), (d) all obligations issued or assumed as the deferred purchase price of property or services purchased (other than trade debt incurred in the ordinary course of business and due within six months of the incurrence thereof), (e) the principal portion of all obligations under Capitalized Leases, (f) all support obligations with respect to funded debt of another entity, (g) the maximum available amount of all standby letters of credit or acceptances or bank guarantees issued or created for the account of such Person (excluding all performance standby letters of credit and performance bank guarantees), (h) all funded debt secured by a Lien on any property, whether or not such funded debt has been assumed, provided that for purposes hereof the amount of such funded debt shall be limited to the lesser of (A) the amount of such funded Debt as to which there is recourse to such property and (B) the fair market value of the property which is subject to such Lien, (i) the outstanding attributed principal amount under any securitization transaction, and (j) the principal balance outstanding under any synthetic lease, tax retention operating lease, off-balance sheet loan or similar off-balance sheet financing product to which the Company is a party, where such transaction is considered borrowed money indebtedness for tax purposes but is classified as an operating lease in accordance with GAAP. The funded debt shall include the funded debt of any partnership or joint venture in which the Company is a general partner or joint venturer, but only to the extent to which there is recourse to the Company for the payment of such funded debt. EBITDA