UV-induced (from 193 to 380 nm) photochemical processes on H2O2 in solid argon (18 K) are studied by using Fourier transform infrared and luminescence spectroscopy. The major photolysis products were identified as (i) a complex of monomeric water with atomic oxygen and (ii) free OH radicals. A three-component photokinetic scheme H2O...O<->H2O2-->2OH describes well all the observed features. The wavelength dependence of the kinetics was measured, which gives the rate constants as a function of excitation wavelength, A novel photoinduced recovery of H2O2 from a water molecule complexed with an oxygen atom is experimentally demonstrated. For the origin of this reaction of importance in various areas, we propose a photoinduced charge transfer between H2O and O with concomitant recombination into H2O2. (C) 1997 American Institute of Physics.