Sir James Irvine Orme Masson FRS FRSE MBE LLD (3 September 1887 – 22 October 1962), generally known as Irvine Masson, was an Australian-born chemist of Scots descent who was Vice-Chancellor of the University of Sheffield from 1938 to 1953. He is usually referred to in documents as J. I. O. Masson.
Irvine Masson was born in Toorak, near Melbourne, the son of Sir David Orme Masson a professor of chemistry at Melbourne University, and his wife, Mary Struthers. He went to Melbourne Grammar School then Melbourne University, achieving a BSc with first class honours in chemistry in 1908. He began medical studies, but reverted to chemistry and in 1910 took up a scholarship in the subject at University College London joining the staff in 1913.
During the First World War he did explosives research at the Royal Arsenal, Woolwich, a practical experience very different from his previous academic work, but which had a major influence on his future research.