* Professor, Department of Biotechnology, IIT-Madras, Chennai 600 036 (2005-Present)
* FFM Chair in Biochemical Engineering, Department of Chemical Engineering, University of Malaya, Kuala Lumpur, Malaysia-50603(1994-2004)
* Professor, Department of Biochemical Engineering and Biotechnology, IIT-Delhi, New Delhi - 110 016(1989-1994)
* Associate Professor, Department of Biochemical Engineering and Biotechnology, IIT-Delhi, New Delhi - 110 016(1986-89)
* Visiting Professor in Biochemical Engineering, Department of Chemical Engineering, University of Malaya, Kuala Lumpur, Malaysia-50603(1988-89)
* Visiting Research Scientist, Department of Genie Biochemique, INSA, Toulouse, France(1983-84)
* Assistant Professor, Indian Institute of Technology: Delhi, New Delhi, India-110 016(1979-86)
* Deputy Group Manager, Process Development, Hindustan Antibiotics Limited, Pimpri, Pune, India(1978-79)
* Assistant Production Officer, Hindustan Antibiotics Limited, Pimpri, Pune, India(1977-78)
* Biochemical Engineer, Hindustan Antibiotics Limited, Pimpri, Pune, India(1976-77)
* Research Assistant, University of Pennsylvania, USA(1971-75)
* Teaching Assistant, Clarkson University, USA(1969-71)