The photocatalytic decomposition characteristics of individual and binary vapors of benzene, toluene, and ethylbenzene by a UV reactor were studied. The reactor was custom-designed to have a synergistic effect of photochemical oxidation by ozone generated by UV254+185 nm lamps and photocatalytic oxidation by TiO2 photocatalyst whose surface area was almost doubled by helically inserted TiO2-coated perforated planes. The removal efficiencies of individual vapors of benzene, toluene, and ethylbenzene generally increased in proportion to the relative humidity and oxygen supply. The photocatalytic decomposition kinetics of individual vapors, as well as binary vapors consisting of benzene-toluene, benzene-ethylbenzene, and toluene-ethylbenzene, followed the Langmuir-Hinshelwood (L-H) equation quite well. Maximum elimination capacities of individual vapors were 560 g/m3ㆍday, 630 g/m3ㆍday, and 1,024 g/ m3ㆍday for benzene, toluene, and ethylbenzene, respectively. In view of mutual impact for the photocatalytic decomposition of binary vapors, the reaction rate of the target component was more influenced by the presence of the counter component with lower bond dissociation energy.