Physicist. Nobel Laureate 1925. He studied at the Universities of Göttingen, Munich, and Berlin, and received his Ph.D. in 1911. He continued to work at the University of Berlin with James Franck, and their work on inelastic electron collisions in gases led to the award in 1925 of the Nobel Prize in Physics. His research work was cut short by the entry of Germany into World War I. He entered the army as an officer and was assigned to Pioneer Battalion 35 under the direction of Fritz Haber. This unit was involved in chemical warfare. He was badly injured in a gas attack on the Russian Army in Poland in 1915 when the gas was blown back into his unit when the wind shifted. After a long recuperation, he was released from service and gained his Habilitation degree in 1917. He worked as a Privatdozent at the University of Berlin until 1920, when he took over as head of the Physics Laboratory at the Philips in Eindhoven, The Netherlands. In 1925 he became Professor of Physics at the University of Halle and in 1927, he took over the direction of the Physical Institute of the Technical University of Charlottenburg. After the Nazi takeover, he lost his position due to his Jewish background, but was semi-protected due to his war service and the fact that his family had converted to Lutheranism in his youth. He was permitted to work as Director of the Siemens-Halske Research Institute, where he was involved in research on gaseous diffusion, one of the forerunner technologies needed for the uranium version of the atomic bomb. In April 1945, due to this work, he was taken by the Red Army to the Soviet research institute at Suchumi on the Black Sea, where he continued work on this topic and was awarded the Stalin Prize in 1951. In the fall of 1954, he returned to Germany to work on the East German project for the peaceful uses of atomic energy and was also named the Director of the Physical Institute at the University of Leipzig. He was a member of the Academy of Sciences of the East Germany and was a founding member of the Research Council of East Germany. As such, he was a central figure in the development of atomic physics in East Germany, and received many honors. Today, the German Physical Society awards the Gustav Hertz Prize in his honor, intended for young researchers with particularly noteworthy projects. He is buried in the family plot along with his uncle Heinrich, also a Nobel Laureate in Physics, and both his sons later became physicists as well. He was honored by an East German postage stamp in 1977.