NO reduction with NH3 over activated carbon-supported copper oxide (CuO/AC) catalyst was studied at low temperatures (30-250 degrees C). The attention was focused on the effects of preparation parameters, reaction temperature and SO2 on the structure and activity of the catalyst. The catalysts show high activities for NO reduction with NH3 in the presence of O-2 at temperatures above 180 degrees C and are gradually deactivated at temperatures below 180 degrees C. Cu2O exists in the catalyst and results in low initial activity but it is easily oxidized into active CuO by O-2 during the NO-NH3-O-2 reaction. Calcination temperature and Cu loading of the catalyst strongly influence the activity and structure of the catalyst. The catalyst with 5 wt% Cu loading and calcined at 250 degrees C shows the highest activity. The activities of the catalysts with higher Cu loadings and/or calcined at higher temperatures are relatively low, mainly derived from aggregation of copper species. The CuO/AC catalyst is greatly deactivated by SO2 due to the formation of CuSO4 which is inactive at low temperatures. (C) 2000 Elsevier Science B.V. All rights reserved.