Novel MnOx catalysts for low-temperature NO reduction with NH3 have been prepared by a simple precipitation method using sodium carbonate. The catalysts thus obtained have exhibited excellent catalytic activity in the temperature range of 75 - 200 ℃ compared with other Mn-based catalysts, which is probably due to its high surface area as well as surface properties. The high catalytic activity is maintained in the presence of 20 vol% water vapor in the feed. The reversible deactivation caused by SO2 was also observed.