This work considers the oxidation of ammonia (NH3) by selective catalytic oxidation (SCO) over a CuO/La2O3 composite catalyst at temperatures between 150 and 400 degrees C. A CuO/La2O3 composite catalyst was prepared by co-precipitation of copper nitrate and lanthanum nitrate at various molar concentrations. This study also considers how the concentration of influent NH3 (C-0 = 1000 ppm), the space velocity (GHSV = 92,000 l/h), the relative humidity (RH = 12%) and the concentration of oxygen (O-2 = 4%) affect the operational stability and the capacity for removing NH3. The catalysts that were characterized using FTIR, XRD, UV-Vis. BET and PSA, have shown that the catalytic behavior is related to the copper (II) oxide, while lanthanum (III) oxide may serve only to provide active sites for the reaction during a catalyzed oxidation run. The experimental results show that the extent of conversion of ammonia by SCO in the presence of the CuO/La2O3 composite catalyst was a function of the molar ratio. The ammonia was removed by oxidation in the absence of CuO/La2O3 composite catalyst, and around 93.0% NH3 reduction was achieved during catalytic oxidation over the CuO/La2O3 (8:2, molar/molar) catalyst at 400 degrees C with an oxygen content of 4.0%. Moreover, the effect of the reaction temperature on the removal of NH3 in the gaseous phase was also monitored at a gas hourly space velocity of under 92,000 h(-1). (C) 2009 Elsevier B.V. All rights reserved.