An investigation was carried out on the decomposition of the dioxin and related compounds in Municipal Solid Waste (MSW) flue gas using a TiO2-V2O5-WO3 catalyst in a NOx selective catalytic reactor. Experiments were done at the flue gas temperature of 210 degrees C. The dioxin and related compounds were classified as particulate and gaseous, and analyzed separately. As a result, high decomposition conversion of dioxin of approximately 90% or higher was obtained. The decomposition conversion of gaseous components was shown to be higher than that of particulate components. Test results were also obtained on coplanar PCBs, which demonstrated behavior similar to the dioxin in the catalyst.