Diebner also served as the director of the Nuclear Research Council and a Reich Planning Officer for the German Army until its surrender to Allied Powers in 1945. After the war, Diebner was incarcerated in the United Kingdom and repatriated back to West-Germany in early 1946. Shortly after his return, Diebner became director and joint owner of DURAG-Apparatebau GmbH and he was a member of the supervisory board of the Gesellschaft zur Kernenergieverwertung in Schiffbau und Schiffahrt m.b.H