Removal of nitrogen oxides using a non-thermal plasma process combined with catalyst was investigated. In this system, selective catalytic reduction of nitrogen oxides is affected by the operating condition of the plasma process, and thus the characteristics of the plasma process were separately examined before combining two processes. The oxidation of NO to NO2 in the plasma reactor greatly decreased as the temperature increased, which implies that an additive to increase the oxidation rate is necessary. In the presence of ethylene used as an additive, the oxidation of NO to NO2 was largely enhanced at relatively high temperatures in the range of 100-200 ℃. The removal efficiency of NOx on the catalyst(V2O5/TiO2) was found to get higher as the ratio of NO2 to NO increased by the plasma discharge. The byproduct formaldehyde formed from ethylene in the plasma reactor could be completely removed in the catalytic reactor while significant amount of carbon monoxide and ammonia slip were observed. The plasma-catalyst system used in this study was able to remove 80% of NOx or more at temperature range of 100 to 200 ℃ that is much lower than typical temperature window of selective catalytic reduction(300-350 ℃).