He was born the son of the Rev. G.P. Rees of Melbourne, Australia and educated at Carey Baptist Grammar School, at Kew, Victoria, Australia. He then worked part-time as a laboratory assistant at Melbourne University whilst studying for a Chemistry degree, which he obtained in 1936. After further study for an M.Sc (awarded in 1938) he travelled to England to work at Imperial College. As war had broken out en route he found himself investigating potential war gases, for which he was awarded a PhD in 1941.