** **

**Exhibit 12.1**

 

**Section 302 Certification**

 

I, Paul Hyland certifythat:

 

1. I have reviewed thisannual report on Form 20-F (as amended by this Form 20-F/A Amendment No. 1)for the fiscal year ended December 31, 2009 of AIXTRON Aktiengesellschaft(the “Company”);

 

2. Based on my knowledge,this report does not contain any untrue statement of a material fact or omit tostate a material fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading withrespect to the period covered by this report;

 

3. Based on my knowledge,the financial statements, and other financial information included in thisreport, fairly present in all material respects the financial condition,results of operations and cash flows of the Company as of, and for, the periodspresented in this report.

 

4. The Company’s othercertifying officer and I are responsible for establishing and maintainingdisclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal controls over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the Company and have:

 

(a) Designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to theCompany, including its consolidated subsidiaries, is made known to us by otherswithin those entities, particularly during the period in which this report isbeing prepared;

 

(b) Designed such internal control over financialreporting, or caused such internal control over financial reporting to bedesigned under our supervision, to provide reasonable assurance regarding thereliability of financial reporting and the preparation of financial statementsfor external purposes in accordance with generally accepted accountingprinciples;

 

(c) Evaluated the effectiveness of the Company’sdisclosure controls and procedures and presented in this report our conclusionsabout the effectiveness of the disclosure controls and procedures, as of theend of the period covered by this report based on such evaluation; and

 

(d) Disclosed in this report any change in theCompany’s internal control over financial reporting that occurred during theperiod covered by the annual report that has materially affected, or isreasonably likely to materially affect, the Company’s internal control overfinancial reporting; and

 

5. The Company’s othercertifying officer and I have disclosed, based on our most recent evaluation ofinternal control over financial reporting, to the Company’s auditors and theAudit Committee of the Company’s board of directors (or persons performing theequivalent functions):

 

(a) All significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the Company’s abilityto record, process, summarize and report financial information; and

 

(b) Any fraud, whether or not material, thatinvolves management or other employees who have a significant role in theCompany’s internal control over financial reporting.

 

Date:  June 21, 2010

 
| /s/    PAUL  HYLAND |                                                 |
|-----------------------------------------|------------------------------------------------------|
|                                    |                                                 |   |
| Name:                                   | **Paul  Hyland**                                     |   |
|                                    | ** **                                           |   |
| Title:                                  | **Chairman,  President and Chief Executive Officer** |   |

 

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