Frederick Sydney Dainton, Baron Dainton FRSFRSE (11 November 1914 – 5 December 1997) was an English academic chemist and university administrator.
A graduate of Oxford and Cambridge, he was Professor of Physical Chemistry at the University of Leeds, Vice-Chancellor of the University of Nottingham, Professor of Chemistry at Oxford and Chancellor of the University of Sheffield. He was elected a fellow of the Royal Society in 1957 (Davy Medal 1969, Faraday Medal 1974), knighted in 1971 and was elevated to a life peerage as Baron Dainton, of Hallam Moors in the County of South Yorkshire in 1986.
Dainton was born in Sheffield on 11 November 1914, the son of George Whalley Dainton (born 1857), a Clerk of Works to a building contractor, and his second wife Mary Jane Bottrill, as the youngest of nine children. He obtained a scholarship to the Central Secondary School in Sheffield, but it was in the public library that he became enthused of chemistry by reading the books of Sidgwick and Hinshelwood. He won an Exhibition at St. John's College, Oxford with a supplementary grant and loan from the City of Sheffield, which enabled him to study chemistry, gaining a first class degree in 1937.
He then moved to Cambridge working on under Norrish. Being short-sighted he was unfit for military service, and stayed to teach at Cambridge during the Second World War. It was during this period that he met and in 1942 married a zoology research student, Barbara Hazlitt Wright (died 12 April 2009). They were married for 55 years, and had a son and two daughters.