Abstract: A photochemical reactor system employing an optical fibers in the form of a cable to transmit light to solid-supported TiO.sub.2 -containing photocatalyst is disclosed. Light energy is transmitted to TiO.sub.2 -containing particles, chemically anchored onto one or more quartz fiber cores, via radial refraction of light out of each fiber. TiO.sub.2 -containing coating layer minimizes the interfacial surface area of the quartz core and TiO.sub.2 -containing particles and operation with incident irradiation angles near 90.degree. enhance light propagation along the fibers. A maximum quantum efficiency of .phi.=1.1% for the oxidation of 4-chlorophenol was achieved. Fiber efficiency permits the light source to be separated from the photocatalyst.