The oxidation of xylene and its irradiation byproducts in air using TiO2 was studied under electron beam (EB) irradiation for the purification of ventilation gases emitted from paint factories. EB irradiation experiments were mainly performed under two different conditions: a TiO2. pellet layer was placed in an irradiation or a non-irradiation space. The results revealed that xylene was decomposed and CO was formed in the gas phase of the irradiation space irrespective of the presence of TiO2 pellets, while CO2 was produced in the gas phase of the irradiation space and on the surface of TiO2 pellets. The total CO2 concentration increased when the pellet layer was in the non-irradiation space. On the other hand, the concentration of CO2 produced on the surface of the TiO2 pellets in the irradiation space was higher than that in a non-irradiation space.