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.