Activated carbon honeycomb supported manganese and cerium oxides (MnOx-CeO2/ACH) catalysts were investigated for selective catalytic reduction (SCR) of NO at low temperatures of 80-200 degrees C. Compared with ACH supported manganese oxide catalyst (MnOx/ACH), MnOx-CeO2/ACH catalysts show much higher SCR activity and higher selectivity to N-2. NO conversion can be improved by the addition of CeO2 from less than 50% to 100% at 80-160 degrees C. The N-2 selectivity of higher than 99.8% is obtained over the Ce(1)Mn/ACH catalyst at 80-200 degrees C. Results indicate that the addition of CeO2 improves the distribution of MnOx and enhances the oxidation of NO to NO2, producing more absorbed NO3- on the catalyst surface, which is then reduced into N-2 by NH3. These behaviors account for the promoting effect of CeO2 on the SCR activity.