In the reactions reviewed, an organic molecule under irradiation catalyzes a chemical reaction. The activation is based either on hydrogen or on electron transfer. Commonly used photoorganocatalysts are aromatic ketones, quinones, heterocycles, dyes; intermediates formed are radicals, radical ions and ions from precursors such as alkanes, alkenes, amines, ethers etc. Oxidation (mainly oxygenation) and reduction processes are obtained along with the α-functionalization of amines and ketones, conjugate additions, cycloadditions etc. The key characteristic of the method is the smooth generation of highly reactive intermediates under mild conditions.