Decomposition of ozone at room temperature was investigated by comparing between commercial monolithic ozone decomposition catalyst (ODC; MnO2) filter and monolithic photocatalyst (TiO2) filter. The effects of residence time, UV (ultraviolet, A type) irradiation, and upstream ozone concentration on the ozone conversion were discussed. UV ray was irradiated using four BLB(black light blue) lamps(λ: 310～400nm) of constant intensity. The upstream concentration of ozone was controlled by an electrostatic ozone generator. For ODC performance, the presence of UV irradiation slightly affected initial ozone conversion compared with no UV irradiation condition. However, for photocatalyst, the ozone was highly decomposed in the presence of UV irradiation. Long time performances of the both catalysts were evaluated by a real-time ozone monitoring system during 120 hours. The results show that the UV irradiation enhanced the ozone conversion for the both catalysts.