<PAGE>

    As filed with the Securities and Exchange Commission on October 13, 2000
                                                Registration No. 333-
================================================================================
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                           ________________________

                                   FORM S-8
                            REGISTRATION STATEMENT
                                     Under
                          THE SECURITIES ACT OF 1933
                           ________________________

                                  ITXC CORP.
            (Exact name of registrant as specified in its charter)

           Delaware                                        22-35-31960
 (State or other jurisdiction                           (I.R.S. employer
of incorporation or organization)                    identification number)

              600 College Road East, Princeton, New Jersey 08540
              (Address of principal executive offices; zip code)
                           ________________________

                        eFusion, Inc. Stock Option Plan
                           (Full title of the plan)

                               Edward B. Jordan
             Executive Vice President and Chief Financial Officer
                                  ITXC Corp.
              600 College Road East, Princeton, New Jersey 08540

                                (609) 419-1500
                     (Name, address and telephone number,
                  including area code, of agent for service)

                                   Copy to:
                           Peter H. Ehrenberg, Esq.
                             Lowenstein Sandler PC
                             65 Livingston Avenue
                          Roseland, New Jersey  07068
                                (973) 597-2500
                           ________________________

                        Calculation of Registration Fee
<TABLE>
<CAPTION>
===========================================================================================================================
                                                         Proposed                  Proposed
Title of Securities          Amount to be            Maximum Offering         Maximum Aggregate            Amount of
to be Registered              Registered           Price per Share (2)        Offering Price (2)        Registration Fee
---------------------------------------------------------------------------------------------------------------------------
<S>                     <C>                      <C>                       <C>                       <C>
Common Stock, par
 value $0.001 per       574,942 shares (1)               $10.91                  $6,272,617                 $1,656
 share
===========================================================================================================================
</TABLE>

(1)  Plus such additional shares of  Common Stock as may be issuable pursuant to
the anti-dilution provisions of the applicable plan.

(2)  Estimated solely for the purpose of calculating the registration fee
pursuant to Rule 457(c) and (h) of the Securities Act of 1933 on the basis of
the average of the high and low sale prices for a share of Common Stock on the
National Market System of NASDAQ on October 10, 2000.
================================================================================
<PAGE>

          PART II  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Certain Documents by Reference

     The SEC allows us to "incorporate" into this Registration Statement
information we file with it in other documents.  This means that we can disclose
important information to you by referring to other documents that contain that
information.  The information incorporated by reference is considered to be part
of this Registration Statement, and information we file later with the SEC will
automatically update and supersede this information.  We incorporate by
reference the documents listed below, except to the extent information in those
documents is different from the information contained in this Registration
Statement, and all future documents filed with the SEC under Sections 13(a),
13(c), 14 or 15(d) of the Securities Exchange Act of 1934 until we terminate the
offering of these shares:

          (a) Our Annual Report on Form 10-K for the year ended December 31,
1999;

          (b)  Our Quarterly Reports on Form 10-Q for the quarters ended March
31, 2000 and June 30, 2000;  and

          (c) The description of our Common Stock set forth in the Registration
Statement on Form 8-A filed by us with the SEC pursuant to Section 12 of the
Exchange Act and declared effective by the SEC on September 27, 1999 .

Item 4.  Description of Securities

          Not applicable.

Item 5.  Interests of Named Experts and Counsel

          Not Applicable.

Item 6.  Indemnification of Directors and Officers

     Under Section 145 of the Delaware General Corporation Law (DGCL), a
corporation has the power to indemnify directors and officers under certain
prescribed circumstances and subject to certain limitations against certain
costs and expenses, including attorneys' fees actually and reasonably incurred
in connection with any action, suit or proceeding, whether civil, criminal,
administrative or investigative, to which any of them is a party by reason of
his being a director or officer of the corporation if it is determined that he
acted in good faith and in a manner he believed to be in (or not opposed to) the
interests of the corporation, and, in the case of a criminal proceeding, he had
no reason to believe his conduct was unlawful. Our certificate of incorporation
provides that we will indemnify any person who was or is a party or is
threatened to be made a party to any threatened, pending or completed action,
suit or proceeding by reason of the fact that he is or was a director or officer
of ITXC, or is or was serving at our request as a director, officer, employee,
manager or agent of another entity, against certain liabilities, costs and
expenses. It further permits us to maintain insurance on behalf of any person
who is or was a director, officer, employee or agent of ITXC, or is or was
serving at our request as a director,

                                       2
<PAGE>

officer, employee or agent of another entity against any liability asserted
against such person and incurred by such person in any such capacity or arising
out of his status as such, whether or not we would have the power to indemnify
such person against such liability under the DGCL.

     Section 102(b)(7) of the DGCL permits a corporation, in its certificate of
incorporation, to limit or eliminate, subject to certain statutory limitations,
the personal liability of directors to the corporation or its stockholders for
monetary damages for breaches of fiduciary duty, as a director except for
liability (a) for any breach of the director's duty of loyalty to the
corporation or its stockholders, (b) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (c) under
Section 174 of the DGCL, or (d) for any transaction from which the director
derived an improper personal benefit. Article NINTH of our Certificate of
Incorporation contains the following provision regarding limitation of liability
of our directors and officers:

     "No director of the Corporation shall be liable to the Corporation or its
     stockholders for monetary damages for breach of fiduciary duty as a
     director, except for  liability (i) for any breach of the director's duty
     of loyalty to the Corporation or its stockholders, (ii) for acts or
     omissions not in good faith or which involve intentional misconduct or a
     knowing violation of law, (iii) under Section 174 of the General
     Corporation Law of the State of Delaware, or (iv) for any transaction from
     which the director derived an improper personal benefit."


Item 7.  Exemption From Registration Claimed

          Not applicable.

Item 8.  Exhibits

          The Exhibits accompanying this Registration Statement are listed on
the accompanying Exhibit Index.

Item 9.  Undertakings

          (a) The undersigned registrant hereby undertakes:

          (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

              (i)   To include any prospectus required by Section 10(a)(3) of
the Securities Act of 1933;

              (ii)  To reflect in the prospectus any acts or events arising
after the effective date of the registration statement (or the most recent post-
effective amendment thereof) which, individually or in the aggregate, represent
a fundamental change in the information set forth in the registration statement.
Notwithstanding the foregoing, any increase or decrease in volume of securities
offered (if the total dollar value of securities offered would not exceed that
which was

                                       3
<PAGE>

registered) and any deviation from the low or high end of the estimated maximum
offering range may be reflected in the form of prospectus filed with the
Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume
and price represent no more than a 20% change in the maximum aggregate offering
price set forth in the "Calculation of Registration Fee" table in the effective
registration statement;

              (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the registration statement or
any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed with or furnished to the
Commission by the registrant pursuant to Section 13 or Section 15(d) of the
Securities Exchange Act of 1934 that are incorporated by reference in the
registration statement.

          (2) That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

          (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

          (c) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable.  In the event that a claim for indemnification
against such liabilities (other than the payment by the registrant of expenses
incurred or paid by a director, officer or controlling person of the registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                       4
<PAGE>

                                   SIGNATURES

          Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Princeton, State of New Jersey, on the 13th day of
October, 2000.

                                    ITXC CORP.



                                    By: /s/ Edward B. Jordan
                                      Edward B. Jordan,
                                      Executive Vice President



     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on the 13th  day of October, 2000.

Signature                                   Title
---------                                   -----

/s/ Tom Evslin*                             Chairman, President and
--------------------------------------      Chief Executive Officer
Tom Evslin

/s/ John G. Musci*                          Director
--------------------------------------
John G. Musci

/s/ Edward B. Jordan                        Chief Financial and Accounting
--------------------------------------      Officer and Director
Edward B. Jordan

                                            Director
--------------------------------------
William P. Collatos

                                            Director
--------------------------------------
Elon A. Ganor

/s/ Frederick R. Wilson*                    Director
--------------------------------------
Frederick R. Wilson



*By: /s/ Edward B. Jordan
    ----------------------------------
    Edward B. Jordan, Attorney-in-Fact

                                       5
<PAGE>

                                 EXHIBIT INDEX

     4.1     The Registrant's Third Restated Certificate of
             Incorporation, as amended.

     4.2     The Registrant's By-Laws are incorporated by reference to Exhibit
             3.2 to the Registrant's Quarterly Report on Form 10-Q for the
             quarter ended March 31, 2000.

     5.1     Opinion of Lowenstein Sandler PC.

     23.1    Consent of Ernst & Young LLP.

     23.2    Consent of Lowenstein Sandler PC is included in Exhibit 5.1.

     24.1    Power of Attorney.

                                       6
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "FORM S-8", "secsgml_size_bytes": 15163}]
{"company-data": {"conformed-name": "ITXC CORP", "cik": "0001061895", "assigned-sic": "4813", "irs-number": "223531960"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-47902", "film-number": "739673"}, "business-address": {"street1": "600 COLLEGE ROAD EAST", "city": "PRINCETON", "state": "NJ", "zip": "08540", "phone": "6094191500"}, "mail-address": {"street1": "600 COLLEGE ROAD EAST", "city": "PRINCETON", "state": "NJ", "zip": "08540"}}
As filed with the Securities and Exchange Commission on October 13, 2000
                                                Registration No. 333-
================================================================================
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                           ________________________

                                   FORM S-8
                            REGISTRATION STATEMENT
                                     Under
                          THE SECURITIES ACT OF 1933
                           ________________________

                                  ITXC CORP.
            (Exact name of registrant as specified in its charter)

           Delaware                                        22-35-31960
 (State or other jurisdiction                           (I.R.S. employer
of incorporation or organization)                    identification number)

              600 College Road East, Princeton, New Jersey 08540
              (Address of principal executive offices; zip code)
                           ________________________

                        eFusion, Inc. Stock Option Plan
                           (Full title of the plan)

                               Edward B. Jordan
             Executive Vice President and Chief Financial Officer
                                  ITXC Corp.
              600 College Road East, Princeton, New Jersey 08540

                                (609) 419-1500
                     (Name, address and telephone number,
                  including area code, of agent for service)

                                   Copy to:
                           Peter H. Ehrenberg, Esq.
                             Lowenstein Sandler PC
                             65 Livingston Avenue
                          Roseland, New Jersey  07068
                                (973) 597-2500
                           ________________________

                        Calculation of Registration Fee
===========================================================================================================================
                                                         Proposed                  Proposed
Title of Securities          Amount to be            Maximum Offering         Maximum Aggregate            Amount of
to be Registered              Registered           Price per Share (2)        Offering Price (2)        Registration Fee
---------------------------------------------------------------------------------------------------------------------------
Common Stock, par
 value $0.001 per       574,942 shares (1)               $10.91                  $6,272,617                 $1,656
 share
===========================================================================================================================
(1)  Plus such additional shares of  Common Stock as may be issuable pursuant to
the anti-dilution provisions of the applicable plan.

(2)  Estimated solely for the purpose of calculating the registration fee
pursuant to Rule 457(c) and (h) of the Securities Act of 1933 on the basis of
the average of the high and low sale prices for a share of Common Stock on the
National Market System of NASDAQ on October 10, 2000.
================================================================================
PART II  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Certain Documents by Reference

     The SEC allows us to "incorporate" into this Registration Statement
information we file with it in other documents.  This means that we can disclose
important information to you by referring to other documents that contain that
information.  The information incorporated by reference is considered to be part
of this Registration Statement, and information we file later with the SEC will
automatically update and supersede this information.  We incorporate by
reference the documents listed below, except to the extent information in those
documents is different from the information contained in this Registration
Statement, and all future documents filed with the SEC under Sections 13(a),
13(c), 14 or 15(d) of the Securities Exchange Act of 1934 until we terminate the
offering of these shares:

          (a) Our Annual Report on Form 10-K for the year ended December 31,
1999;

          (b)  Our Quarterly Reports on Form 10-Q for the quarters ended March
31, 2000 and June 30, 2000;  and

          (c) The description of our Common Stock set forth in the Registration
Statement on Form 8-A filed by us with the SEC pursuant to Section 12 of the
Exchange Act and declared effective by the SEC on September 27, 1999 .

Item 4.  Description of Securities

          Not applicable.

Item 5.  Interests of Named Experts and Counsel

          Not Applicable.

Item 6.  Indemnification of Directors and Officers

     Under Section 145 of the Delaware General Corporation Law (DGCL), a
corporation has the power to indemnify directors and officers under certain
prescribed circumstances and subject to certain limitations against certain
costs and expenses, including attorneys' fees actually and reasonably incurred
in connection with any action, suit or proceeding, whether civil, criminal,
administrative or investigative, to which any of them is a party by reason of
his being a director or officer of the corporation if it is determined that he
acted in good faith and in a manner he believed to be in (or not opposed to) the
interests of the corporation, and, in the case of a criminal proceeding, he had
no reason to believe his conduct was unlawful. Our certificate of incorporation
provides that we will indemnify any person who was or is a party or is
threatened to be made a party to any threatened, pending or completed action,
suit or proceeding by reason of the fact that he is or was a director or officer
of ITXC, or is or was serving at our request as a director, officer, employee,
manager or agent of another entity, against certain liabilities, costs and
expenses. It further permits us to maintain insurance on behalf of any person
who is or was a director, officer, employee or agent of ITXC, or is or was
serving at our request as a director,

                                       2
officer, employee or agent of another entity against any liability asserted
against such person and incurred by such person in any such capacity or arising
out of his status as such, whether or not we would have the power to indemnify
such person against such liability under the DGCL.

     Section 102(b)(7) of the DGCL permits a corporation, in its certificate of
incorporation, to limit or eliminate, subject to certain statutory limitations,
the personal liability of directors to the corporation or its stockholders for
monetary damages for breaches of fiduciary duty, as a director except for
liability (a) for any breach of the director's duty of loyalty to the
corporation or its stockholders, (b) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (c) under
Section 174 of the DGCL, or (d) for any transaction from which the director
derived an improper personal benefit. Article NINTH of our Certificate of
Incorporation contains the following provision regarding limitation of liability
of our directors and officers:

     "No director of the Corporation shall be liable to the Corporation or its
     stockholders for monetary damages for breach of fiduciary duty as a
     director, except for  liability (i) for any breach of the director's duty
     of loyalty to the Corporation or its stockholders, (ii) for acts or
     omissions not in good faith or which involve intentional misconduct or a
     knowing violation of law, (iii) under Section 174 of the General
     Corporation Law of the State of Delaware, or (iv) for any transaction from
     which the director derived an improper personal benefit."

Item 7.  Exemption From Registration Claimed

          Not applicable.

Item 8.  Exhibits

          The Exhibits accompanying this Registration Statement are listed on
the accompanying Exhibit Index.

Item 9.  Undertakings

          (a) The undersigned registrant hereby undertakes:

          (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

              (i)   To include any prospectus required by Section 10(a)(3) of
the Securities Act of 1933;

              (ii)  To reflect in the prospectus any acts or events arising
after the effective date of the registration statement (or the most recent post-
effective amendment thereof) which, individually or in the aggregate, represent
a fundamental change in the information set forth in the registration statement.
Notwithstanding the foregoing, any increase or decrease in volume of securities
offered (if the total dollar value of securities offered would not exceed that
which was

                                       3
registered) and any deviation from the low or high end of the estimated maximum
offering range may be reflected in the form of prospectus filed with the
Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume
and price represent no more than a 20% change in the maximum aggregate offering
price set forth in the "Calculation of Registration Fee" table in the effective
registration statement;

              (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the registration statement or
any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed with or furnished to the
Commission by the registrant pursuant to Section 13 or Section 15(d) of the
Securities Exchange Act of 1934 that are incorporated by reference in the
registration statement.

          (2) That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

          (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

          (c) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable.  In the event that a claim for indemnification
against such liabilities (other than the payment by the registrant of expenses
incurred or paid by a director, officer or controlling person of the registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                       4
SIGNATURES

          Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Princeton, State of New Jersey, on the 13th day of
October, 2000.

                                    ITXC CORP.

                                    By: /s/ Edward B. Jordan
                                      Edward B. Jordan,
                                      Executive Vice President

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on the 13th  day of October, 2000.

Signature                                   Title
---------                                   -----

/s/ Tom Evslin*                             Chairman, President and
--------------------------------------      Chief Executive Officer
Tom Evslin

/s/ John G. Musci*                          Director
--------------------------------------
John G. Musci

/s/ Edward B. Jordan                        Chief Financial and Accounting
--------------------------------------      Officer and Director
Edward B. Jordan

                                            Director
--------------------------------------
William P. Collatos

                                            Director
--------------------------------------
Elon A. Ganor

/s/ Frederick R. Wilson*                    Director
--------------------------------------
Frederick R. Wilson

*By: /s/ Edward B. Jordan
    ----------------------------------
    Edward B. Jordan, Attorney-in-Fact

                                       5
EXHIBIT INDEX

     4.1     The Registrant's Third Restated Certificate of
             Incorporation, as amended.

     4.2     The Registrant's By-Laws are incorporated by reference to Exhibit
             3.2 to the Registrant's Quarterly Report on Form 10-Q for the
             quarter ended March 31, 2000.

     5.1     Opinion of Lowenstein Sandler PC.

     23.1    Consent of Ernst & Young LLP.

     23.2    Consent of Lowenstein Sandler PC is included in Exhibit 5.1.

     24.1    Power of Attorney.

                                       6