Otto Hahn, the son of a glazier, was born in Frankfurt am Main, Germany, on 8th March, 1879. He studied chemistry at the University of Marburg and obtained his doctorate in 1901. Afterwards he became a lecturer at the university.
On the outbreak of the First World War Hahn was recruited into the German Army. His scientific knowledge was acknowledged and he became a chemical-warfare specialist and organized the use of Chlorine Gas and Mustard Gas against British and French troops.
After the war Hahn resumed working with Lise Meitner and together they discovered protactinium (1918) and nuclear isomers (1921). Over the next few years they devoted their time to researching the application of radioactive methods to chemical problems.
In the 1930s Hahn became interested in the research being carried out by Enrico Fermi and Emilio Segre at the University of Rome. This included experiments where elements such as uranium were bombarded with neutrons. By 1935 the two men had discovered slow neutrons, which have properties important to the operation of nuclear reactors.
Hahn and Lise Meitner were now joined by Fritz Strassmann and discovered that uranium nuclei split when bombarded with neutrons. In 1938 Meitner, like other Jews in Germany, was dismissed from her university post. She moved to Sweden and in 1939 wrote a paper on nuclear fission with her nephew, Otto Frisch, where they argued that by splitting the atom it was possible to use a few pounds of uranium to create the explosive and destructive power of many thousands of pounds of dynamite.
During the Second World War Hahn and Fritz Strassmann continued to work in the field of nuclear physics but they made no attempt to turn their knowledge into a military weapon. Hahn had a strong dislike for Adolf Hitler and his government and told a friend: "If my work would lead to Hitler having an atomic bomb I would kill myself."
In April, 1945, Allied forces arrested German scientists such as Hahn, Werner Heisenberg, Carl von Weizsacker, Max von Laue, Karl Wirtz, and Walter Gerlach. These men were now taken to England where they were questioned to see if they had discovered how to make atomic weapons.
When he was released Hahn became president of the Max Planck Society for the Advancement of Science. In 1966 Hahn shared with Lise Meitner and Fritz Strassmann the Enrico Fermi Award. Otto Hahn died in West Germany on 28th July, 1968.