In 1953, Strassmann gave up the directorship, choosing instead to focus on his research and scholarship at the University of Mainz. He succeeded in building up the departments capabilities, and he worked directly with students. Strassmann began these undertakings at the University of Mainz with a few scattered rooms and very little money.  He negotiated with the university and with Badische Anilin- und Soda-Fabriken (B.A.S.F.) to fund an institute for the chemical sciences at the university with a focus on nuclear chemistry. He also lobbied the German federal government to fund a neutron generator, a nuclear reactor for research purposes, and a special institute for nuclear chemistry.  Strassmans creation, the Institute for Nuclear Chemistry, officially opened on 3 April 1967.
In 1957 Strassmann was one of the  Göttinger Achtzehn (Göttingen eighteen), a group of leading nuclear researchers of the Federal Republic of Germany who wrote a manifesto (Göttinger Manifest, Göttinger Erklärung) opposing chancellor Konrad Adenauer and defense secretary Franz-Josef Straußs plans to equip the Bundeswehr, Western Germanys army, with tactical nuclear weapons.
Strassmann retired in 1970. He died on 22 April 1980 in Mainz.