##### 



As Filed with the Securities and Exchange Commission on
February 2, 2006








UNITED STATES SECURITIES AND EXCHANGE COMMISSION


Washington, D.C. 20549


Form 20-F/A


(Amendment No. 1)


|           |  |                                                                                                     
|---------- |  | ----------------------------------------------------------------------------------------------------
|(Mark One) |  |                                                                                                     
|o          |  | REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR
    12(g) OF THE SECURITIES EXCHANGE ACT OF 1934
|          
|           |  | OR                                                                                                  
|          
|þ          |  | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
    SECURITIES EXCHANGE ACT OF 1934            
|          
|           |  | For the fiscal year ended December 31, 2005                                                         
|          
|           |  | OR                                                                                                  
|          
|o          |  | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
    SECURITIES EXCHANGE ACT OF 1934        
|          
|           |  | For the transition period
    from           to                                                     
|          
|o          |  | SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
    SECURITIES EXCHANGE ACT OF 1934     
|          
|           |  | Date of event requiring this shell company report                                                   

Ciba Specialty Chemicals Holding Inc.


(Exact name of Registrant as specified in its charter)


Switzerland


(Jurisdiction of incorporation or organization)


Klybeckstrasse 141


4002 Basel


Switzerland


(Address of principal executive offices)


Securities registered or to be registered pursuant to
Section 12(b) of the Act.


|                                                                                                                    |  |                                          
|------------------------------------------------------------------------------------------------------------------- |  | -----------------------------------------
|Title of Each Class                                                                                                 |  | Name of Each Exchange on Which Registered
|                                                                                                                    |  |                                          
|American Depositary shares,
    Each representing one half of one ordinary share,
    nominal value CHF 1 per share |  | New York Stock Exchange                  
|Ordinary shares, par value CHF 1 per share*                                                                         |  |                                          

Securities registered or to be registered pursuant to
Section 12(g) of the Act. None





(Title of Class)


Securities for which there is a reporting obligation pursuant
to Section 15(d) of the Act. None





(Title of Class)


o þ









þ o


þ o


12b-2


þ o o


o þ


12b-2 o þ







|  |                                                                                                                                                                               
|- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|* | Not for trading but only in connection with the registration of
    the American Depositary Shares pursuant to the requirements of
    the Securities and Exchange Commission.









---



##### 



Explanatory Note







Introduction


20-F











Currency Translation







Cautionary Statement Regarding Forward-Looking Information




1



---



##### 






Signature


20-F




| |                                       
| | --------------------------------------
| | Ciba Specialty Chemicals Holding Inc.,



| |     |                   
| | --- | ------------------
| | By: | /s/ Michael Jacobi

| |                     
| | --------------------
| |                     
| | Name: Michael Jacobi

| |        |                        
| | ------ | -----------------------
| | Title: | Chief Financial Officer



108



---



##### 





Section 302 Certification


CERTIFICATIONS


I, Armin Meyer, certify that:




| |    |                                                                                                                                                                                                                                                                                                                           
| | -- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 1. | I have reviewed this annual report on Form 20-F of Ciba
    Specialty Chemicals Holding Inc.;                                                                                                                                                                                                                             
|
| | 2. | Based on my knowledge, this report does not contain any untrue
    statement of a material fact or omit to state a material fact
    necessary to make the statements made, in light of the
    circumstances under which such statements were made, not
    misleading with respect to the period covered by this report;
|
| | 3. | Based on my knowledge, the financial statements, and other
    financial information included in this report, fairly present in
    all material respects the financial condition, results of
    operations and cash flows of the company as of, and for, the
    periods presented in this report;                      
|
| | 4. | The companys other certifying officer(s) and I are
    responsible for establishing and maintaining disclosure controls
    and procedures (as defined in Exchange Act Rules 13a-15(e)
    and 15d-15(e)) for the company and have:                                                                                      



| |     |                                                                                                                                                                                                                                                                                                                                                                                                
| | --- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (a) | Designed such disclosure controls and procedures, or caused such
    disclosure controls and procedures to be designed under our
    supervision, to ensure that material information relating to the
    company, including its consolidated subsidiaries, is made known
    to us by others within those entities, particularly during the
    period in which this report is being prepared;
|
| | (b) | Evaluated the effectiveness of the companys disclosure
    controls and procedures and presented in this report our
    conclusions about the effectiveness of the disclosure controls
    and procedures, as of the end of the period covered by this
    report based on such evaluation; and                                                                                               
|
| | (c) | Disclosed in this report any change in the companys
    internal control over financial reporting that occurred during
    the period covered by the annual report that has materially
    affected, or is reasonably likely to materially affect, the
    companys internal control over financial reporting; and                                                                           



| |    |                                                                                                                                                                                                                                                                                                          
| | -- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 5. | The companys other certifying officer(s) and I have
    disclosed, based on our most recent evaluation of internal
    control over financial reporting, to the companys auditors
    and the audit committee of the companys board of directors
    (or persons performing the equivalent functions):



| |     |                                                                                                                                                                                                                                                                                       
| | --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (a) | All significant deficiencies and material weaknesses in the
    design or operation of internal control over financial reporting
    which are reasonably likely to adversely affect the
    companys ability to record, process, summarize and report
    financial information; and
|
| | (b) | Any fraud, whether or not material, that involves management or
    other employees who have a significant role in the
    companys internal control over financial reporting.                                                                                                       





| |                          
| | -------------------------
| | /s/ Armin Meyer          
| |                          
| | Armin Meyer              
| | Chairman of the Board and
| | Chief Executive Officer  



---



##### 





Section 302 Certification


CERTIFICATIONS


I, Michael Jacobi, certify that:




| |    |                                                                                                                                                                                                                                                                                                                           
| | -- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 1. | I have reviewed this annual report on Form 20-F of Ciba
    Specialty Chemicals Holding Inc.;                                                                                                                                                                                                                             
|
| | 2. | Based on my knowledge, this report does not contain any untrue
    statement of a material fact or omit to state a material fact
    necessary to make the statements made, in light of the
    circumstances under which such statements were made, not
    misleading with respect to the period covered by this report;
|
| | 3. | Based on my knowledge, the financial statements, and other
    financial information included in this report, fairly present in
    all material respects the financial condition, results of
    operations and cash flows of the company as of, and for, the
    periods presented in this report;                      
|
| | 4. | The companys other certifying officer(s) and I are
    responsible for establishing and maintaining disclosure controls
    and procedures (as defined in Exchange Act Rules 13a-15(e)
    and 15d-15(e)) for the company and have:                                                                                      



| |     |                                                                                                                                                                                                                                                                                                                                                                                                
| | --- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (a) | Designed such disclosure controls and procedures, or caused such
    disclosure controls and procedures to be designed under our
    supervision, to ensure that material information relating to the
    company, including its consolidated subsidiaries, is made known
    to us by others within those entities, particularly during the
    period in which this report is being prepared;
|
| | (b) | Evaluated the effectiveness of the companys disclosure
    controls and procedures and presented in this report our
    conclusions about the effectiveness of the disclosure controls
    and procedures, as of the end of the period covered by this
    report based on such evaluation; and                                                                                               
|
| | (c) | Disclosed in this report any change in the companys
    internal control over financial reporting that occurred during
    the period covered by the annual report that has materially
    affected, or is reasonably likely to materially affect, the
    companys internal control over financial reporting; and                                                                           



| |    |                                                                                                                                                                                                                                                                                                          
| | -- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 5. | The companys other certifying officer(s) and I have
    disclosed, based on our most recent evaluation of internal
    control over financial reporting, to the companys auditors
    and the audit committee of the companys board of directors
    (or persons performing the equivalent functions):



| |     |                                                                                                                                                                                                                                                                                       
| | --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (a) | All significant deficiencies and material weaknesses in the
    design or operation of internal control over financial reporting
    which are reasonably likely to adversely affect the
    companys ability to record, process, summarize and report
    financial information; and
|
| | (b) | Any fraud, whether or not material, that involves management or
    other employees who have a significant role in the
    companys internal control over financial reporting.                                                                                                       





| |                        
| | -----------------------
| | /s/ Michael Jacobi     
| |                        
| | Michael Jacobi         
| | Chief Financial Officer