Photoreaction of molecular complex composed of ozone and dimethylamine is investigated by matrix-isolation IR and UV-visible spectroscopies. The UV-visible spectrum of the molecular complex isolated in an Ar matrix shows two broad bands in the region between 400 and 700 nm. Upon red-light irradiation (lambda >= 680 nm), dimethylamine-N-oxide is produced by intermolecular oxygen-atom transfer from O-3 to the lone pair on the nitrogen atom of dimethylamine. Dimethylamine-N-oxide isomerizes to N,N-dimethylhydroxylamine by intramolecular hydrogen-atom migration upon the second light irradiation lambda >= 385 nm). The both photoproducts are identified by the DFT calculation at the B3LYP/6-31++G(d,p) level. (C) 2018 Elsevier B.V. All rights reserved.