This paper reports on the degradation of gaseous toluene by the photocatalytic oxidation process. The photocatalyst, TiO2 film, was prepared by the sol-gel method and was coated on porous nickel. The photocatalytic decomposition of toluene was carried out in a recirculating batch reactor. The factors that affect toluene decomposition were studied, including particle size of the catalyst, initial toluene concentration, flow rate of toluene in the reactor, relative humidity and reactive temperature. In addition, deactivation of the catalyst is also discussed. The experiment results showed that toluene can be decomposed effectively by the photocatalytic oxidation process, and that toluene degradation obeys the first-order reaction.