NOx removal characteristics and NO conversion trends were investigated for plasma process, catalytic process, and plasma catalytic hybrid process. In the experiments, we studied effects of the flow rate and the carrier gas on the NO conversion in the plasma process, and effects of ammonia concentration and temperature on the NOx removal in the catalytic process. We also investigated the synergetic effect of a plasma-catalytic hybrid process. Dielectric barrier discharge was combined with V2O5 - WO3/TiO2 catalyst for removing nitrogen oxides. The maximum conversions of nitrogen oxides were approximately 52, 80, and 98% at the temperature of 100, 200, and 300degreesC, respectively. The optimal energy density, ammonia concentration, and ratio of nitrogen oxides exist for the highest removal of nitrogen oxides in the plasma catalytic hybrid process.