Removal of NO and CH4 gases was examined using nonthermal-plasma (NTP)-assisted 12% CuO/15% TiO2/gamma-Al2O3 under four reaction conditions (NO + CH4, NO + CH4 + O-2, NO + CH4 + NTP, and NO + CH4 + O-2 + NTP). Methods of Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), X-ray diffraction (XRD), H-2-temperature-programmed reduction (H-2-TPR), and X-ray photoelectron spectroscopy (XPS) were used to investigate the catalyst characteristics before and after the reactions. The results showed that plasma discharge improved low-temperature reaction activity and addition of O-2 increased NO and CH4 conversion. Pore size distribution of 15% TiO2/gamma-Al2O3 was a typical texture of the alumina support. The specific surface area of 12% CuO/15% TiO2/gamma-Al2O3 changed little before and after the NO + CH4 reaction, but its surface crystalline CuO reduced to Cu2O and Cu, which was found by XPS analysis. After the reaction, highly dispersed CuO and bulk CuO reduction peak of the catalyst vanished after the NO + CH4 reaction. Cu2+ still existed to some extent on the surface of the catalyst after the reaction, compared to a significant increase in Cu+ and Cu-0 species.