After working as a lecturer in chemistry at University College in North Wales for five years, Dostrovsky returned to Israel, joining the Weizmann Institute of Science in Rehovot in 1948, shortly before the Institute's dedication. The Institute's five scientific departments were to be headed by world-class scientists from various countries, but just then the War of Independence broke, and only two of the appointed scientific leaders dared to move to Israel. Dostrovsky, then only 30, filled one of the three vacant leadership positions: he was appointed Head of the Isotope Research Department, a post he held for 17 years.