John Brown is an organic chemist whose interests are directed towards the mechanistic understanding of processes relevant to organic chemical synthesis in both academia and industry, with an emphasis on homogeneous catalysis. He has worked on rhodium-catalysed asymmetric and directed hydrogenations, on catalytic hydroboration, and on palladium-catalysed couplings. His wider interests have included asymmetric autocatalysis and the design and application of ligands to facilitate catalysis.

His independent research career started in Canberra and Bristol, and followed postgraduate research in Manchester (Arthur Birch, FRS) and postdoctoral work at Columbia University, New York (Ronald Breslow, ForMemRS). His first permanent post was at Warwick (1966–1974) followed by a move to Oxford in 1974, where he is now Emeritus both in the university and at Wadham College.

He was recipient of the Royal Society of Chemistry (RSC) Robert Robinson Award (2013) and earlier received the Tilden Lectureship (1991) and the Organometallic Award (1993) from the RSC. He shared the EU Descartes Prize (2001) and received the Pracejus Prize for Stereochemistry from the German Chemical Society (2005).