* Associate Professor, Department of Biotechnology (Jan. 2004 - present); IITMadras, Chennai 600036.
* Assistant Professor, (Oct. 1998-Dec. 2004) Department of Chemistry, IITMadras, Chennai 600036.
* Sr. Scientist, (April 1995 - October 1998); SPIC Pharma R & D Center, Maraimalai Nagar, TN 603209.
* Scientist, (March 1991- March 1995) SPIC Pharma R & D Center, Maraimalai Nagar, TN 603 209.
* Alexander von Humboldt Fellow in Germany (April 1992 - May 1993);Study leave from SPIC.
* Research Associate, (March 1990 - March 1991)Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012.
* Visiting Associate, (June 1988 - October 1989), Laboratory of Bioorganic Chemistry, Oxidation Mechanisms, National Institutes of Health, Bethesda, MD-20892, USA.
* Visiting Fogarty Fellow(June 1985 - May 1988), Laboratory of Bioorganic Chemistry, Oxidation Mechanisms, National Institutes of Health, Bethesda, MD- 20892, USA.
* Research Fellow, (July 1979 - December 1984), Indian Institute of Science, Bangalore.
* Lecturer, (June 1978 - May 1979), Department of Chemistry, Fergusson College, University of Poona, Poona, India.