Exhibit 10.1

FIRST AMENDMENT TO THE

EXECUTIVE EMPLOYMENT AGREEMENT

WITH DAVID HARVEY

WHEREAS, Sigma-Aldrich Corporation (“Company”) and David Harvey (“Executive”)
previously entered into an Executive Employment Agreement (“Agreement”) dated
January 1, 2006 and

WHEREAS, the Company and the Executive desire to amend the Agreement in certain
respects;

NOW, THEREFORE, in consideration of the promises and the mutual agreements
contained herein, the Company and Executive hereby agree to amend the Agreement
as follows:

The first sentence of Section 2.4(a) of the Agreement is amended to read as
follows:

 

2.4(a) General Term. This Agreement shall commence on January 1, 2006 and
terminate on the date of the 2008 Annual General Meeting, as determined by the
Board in it discretion (“Term”). The Term may be extended by the parties by
written agreement for successive additional one-year periods.

IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
first written above.

 

SIGMA-ALDRICH CORPORATION

By:

 

/s/ Kirk Richter

Name:

  Kirk Richter

Title:

  Treasurer and Investor Relations DAVID HARVEY

/s/ David R. Harvey