Zeolites can be used in air cleaning to remove volatile organic compounds (VOCs). This study investigates a filtration system by using zeolite 13X, together with an external oxidizing agent (Ozone) to remove toluene. The removal performance of toluene (1.5 ppm) in gas phase by 3600g zeolite at various ozone concentrations and moisture conditions was studied. The inlet concentration of ozone (0- 6ppm) on the removal of toluene was examined. The experimental results showed that the addition of ozone to the testing system could enhance the conversion factor of toluene from 0.20 to 0.88 at room temperature. The conversion factor of toluene could further increase if more ozone or zeolite was used. The crystal structure and the phase purity of zeolites were verified by powdered X-ray diffraction (PXRD). Adsorptions of H2O and toluene on zeolites were characterized by FT-IR spectral measurements and thermogravimetric methods.