Advances in the chemistry of chlorosulphonyl isocyanate (CSI) contributed by the author's research group at Indian Institute of Technology, Kanpur (1976-94) are highlighted and reviewed in this work. The applications of chlorosulphonyl isocyanate are covered by a large number of patents form several countries around the world viz Belgium, Britain, Canada, China, Europe, France, Germany, India, Italy, Netherlands, Spain, Switzerland, and USA. Chlorosulphonyl Isocyanate has been employed for the synthesis of a large variety of compounds, which are associated with a broad range of useful properties including in therapeutics.