The occurrence of photoinduced hydrogen atom transfer between two remote spots of a molecule is experimentally demonstrated. This photoprocess involves the intermediacy of an intramolecular "crane". In an experimental case study, 7-hydroxy-4-methylquinoline-8-carbaldehyde monomers isolated in low-temperature Ar matrices are investigated. On UV (lambda>295 nm) irradiation, a hydrogen atom is transferred from the O(7)H group to the N(1) atom of the quinoline ring. Subsequent irradiation with UV (lambda>360 nm) light reveals that the phototransformation is partially photoreversible. In the studied hydrogen-atom-transfer process, the exocyclic carbaldehyde group plays the role of an intramolecular crane. The possible application of systems analogous to 7-hydroxy-4-methylquinoline-8-carbaldehyde as optically driven molecular switches is discussed.