Jules Loszynski was a son of Simon Loszynski and Amalia Manasse. On 26 August 1937 he married in Berlin Ruth Beatrice Brandel Reich, a daugher of Baruch Marcus Reich and Herta Neumann. The couple had no children.
Since June 1938 Jules Loszynski and his wife resided in Amsterdam at various addresses; he and his wife Ruth were registered at Bieschboschstraat 56 II on 23 June 1938; they moved to Deur…