The visible-light photolysis of ozone-water van der Waals complexes was evaluated as a potential source of atmospheric hydroxyl radical and/or hydrogen peroxide. These reactions were shown to account for no more than 1.3% of the atmospheric burden of OH and no more than 7% of atmospheric H 2O 2. Upper limits to the production of OH and H 2O 2 were evaluated in static, gas-phase ozone/water mixtures irradiated with natural sunlight. Upper limits to hydroxyl radical concentrations were inferred from the catalytic destruction of ozone. Hydrogen peroxide was determined by purging the bulb contents into a receiving solvent, which was analyzed for H 2O 2 by the peroxyoxalate chemiluminescence technique.