The effects of light on the Ru(bpy)(3)(2+)-catalyzed Belousov-Zhabotinsky (BZ) reaction are investigated. Experiments were carried out on an organic subset of the reaction comprised of bromomalonic acid, sulfuric acid, and Ru(bpy)(3)(2+) as well as on an inorganic subset comprised of bromate, sulfuric acid, and Ru(bpy)(3)(2+). Experiments were also carried out on the full Ru(bpy)(3)(2+)-catalyzed BZ system. The experiments, together with modeling studies utilizing an Oregonator scheme modified to account for the light sensitivity, show that irradiation gives rise to two separate processes: the photochemical production of bromide from bromomalonic acid and the photochemical production of bromous acid from bromate.