Dr Tilak's work has led to the synthesis of new heterocyclic quinonoid dyestuffs of considerable academic and practical value. His studies on hydride transfer and steric factors that control it have enabled elucidation of the mechanism of formation on cyanine and triphenylmethane dyes and have led to the synthesis of a new class of cationoid dyes of potential commercial value and hitherto unknown bicyclic sulphonium salts. Dr Tilak is also well known for his contribution towards the establishment and development of dyestuff industry in India. He has made significant contributions to elucidation of the chemistry of thiophene and its polycyclic derivatives. This work has led to the total synthesis of heterocyclic steroids and a few sulphur-containing compounds which show significant anti-cancer properties.