This study is on the reduction of nitrogen monoxide with CuZSM-5 catalyst of copper oxide compoundsmodified with zeolite of a silica concentration of 1.5% in mass. The reactions of NO with catalysts composed of mordenites (0.75% CM, 1.5% CuM and 2.2% CuM) were studied and the result showed that these compounds are not active. The reaction of NO with CuO and CuO/ï§-Al2O3 compounds was also studied. The reduction of CuO was observed at all temperatures of the experiment. An increase in CuO concentration in the CuO/ï§-Al2O3 catalyst of 0.5 to 1.5% by mass increased its activity. The rate of reaction of NO with CuZSM-5 catalyst was higher than that with the CuO/ï§-Al2O3 catalyst. Results obtained showed that the CuZSM-5 modified catalyst is more active and therefore can be useful for the purification of the emissions of nitrogen monoxide. This work can contribute to the fight against environmental pollution.