Gerischer met his future wife, Renate Gersdorf, at the University of Leipzig where she was doing her diploma work with Conrad Weygand.
In 1949 Gerischer moved his young family to Göttingen to join Bonhöffer as a research associate at the newly established Max Planck Institute for Physical Chemistry.
It was recognized by the newly minted Bodenstein Prize of the Deutsche Bunsen-Gesellschaft, which Gerischer and Klaus Vetter jointly received in 1953.
Gerischer recognized the theoretical implications of semiconductor electrochemistry in charge transfer and its potential applications in photochemistry and photovoltaic devices.
The 1964–1968 period witnessed a flurry of studies from his group on photoelectrochemistry and photosensitization on electrode materials such as ZnO, CdS, GaAs, silver halides, anthracene, and perylene.
Gerischer returned to Berlin in 1970 to assume the directorship of the Fritz Haber Institute of the Max Planck Society, where he continued his studies of electrode kinetics, semiconductor electrochemistry, and photoelectrochemistry.
After becoming Emeritus Director of the Institute, he worked with Adam Heller in 1990–1991 at the University of Texas at Austin on the rate-controlling role of adsorbed oxygen in titania-assisted photocatalytic processes.