The effect of O(2) and H(2)O vapor on the Nitric oxide (NO) removal rate, the NO(2) generation rate and the discharge characteristics were investigated using the dielectric barrier discharge (DBD) reactor at 1 atm pressure and at room temperature (20A degrees). The results showed that the O(2) present in the flue gas always hampered the removal of NO and the generation of N(2)O, but that the O(2) could enhance the generation of NO(2) in the NO/N(2)/O(2) mixtures. Furthermore, with the increase of oxygen, the average discharge current gradually decreases in the reactor. The H(2)O present in N(2)/NO hindered the removal of NO and the generation of NO(2) but had no impact on the average discharge current in the reactor in the NO/N(2)/H(2)O mixtures in which the HNO(2) and HNO(3) was detected. The energy efficiency of the DBD used to remove the NO from the flue gas was also estimated.