Sir Jack Edward Baldwin, FRS (b. London 8 Aug 1938), is a British chemist. He is a former Waynflete Professor of Chemistry at the University of Oxford (1978–2005) and the former head of the organic chemistry department of that university.
He studied at Imperial College, London, and spent most of the years 1969–1978 at MIT, where he published his most significant work — Baldwin's rules for ring closure reactions. In 1978, he moved to Oxford to become head of the Dyson Perrins Laboratory. The laboratory formally closed in 2003, but his group moved to the new research facility, the Chemistry Research Laboratory on Mansfield road, and he is still an active researcher at Oxford.