Professor Man Mohan Sharma was educated at Jodhpur (Rajasthan), Mumbai, and Cambridge, England. He was appointed to the rank of Professor in the Institute of Chemical Technology, Mumbai, when he was just above 27 years of age. He was the youngest ever recipient of S.S Bhatnagar prize in Engineering Sciences in 1973. Professor Sharma was elected a fellow of the Indian National Science Academy in 1976 and later became its president during 1989–1990. The crowning glory came in 1990 with his election as a fellow of the Royal Society, England as the first engineer from India to be elected to this august body. Professor Sharma was elected a foreign associate of the US National Academy of Engineering. He also was the Editor of Chemical Engineering Science, and has been a consultant to chemical industry for 50 years. (Subhas Sikdar): Professor Sharma, Thank you very much for accepting to conduct this conversation with me for this journal. I consider it a special honor to be able to converse with you on matters that span the gamut from science and chemical technologies to what we call progress and the public policy that can shape it. Your entire life has been an inimitable example of technical and pedagogic excellence, and to this day has remained a remarkable inspiration to hundreds of your students and colleagues worldwide. We will traverse those territories shortly, but first I want to engage you in a discussion on sustainability as it relates to the exploits of engineering. As the environmental stewardship dogma moved from waste minimization to pollution prevention to design for the environment eventually arriving at the concept of sustainability, you have had something important to say about all previous concepts through your ideas and research. Given that environmental pollution still is rampant in the Indian cities after all these years of development, I would like to know your ideas of relevance of sustainability to Indian condition and how the country can make significant inroads toward achieving that goal through policy measures, and particularly through the application of cleaner technologies. (M.M. Sharma): Sustainability is of great importance to India, as it is globally. We should refer to all the so-called waste streams as resource with a negative cost. We can give many valuable examples. Take the case of SO2 from smelter gas which has been valorized as H2SO4; similarly H2S from sour natural gas and from hydrodesulphurization which has been converted to S and today a major part of S is from recovered source. India does not have any sulfur mines. Active pharmaceutical ingredients (API) in pharma industry provide a fascinating example as India, along with China, has become a leading supplier for global & Subhas K. Sikdar sikdar.subhas@epa.gov