Photoelectrochemical processes are processes in photoelectrochemistry; they usually involve transforming light into other forms of energy. These processes apply to photochemistry, optically pumped lasers, sensitized solar cells, luminescence, and photochromism.

Freiherr Christian Johann Dietrich Theodor von Grotthuss was a Baltic German scientist known for establishing the first theory of electrolysis in 1806 and formulating the first law of photochemistry in 1817. His theory of electrolysis is considered the first description of the so-called Grotthuss mechanism.