Novel MnOx catalysts for NO reduction at low temperature 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 348-473 K compared with other MnOx-based catalysts, which is probably due to its high surface area as well as framework structure and composition. The high catalytic activity is maintained in the presence of 20 vol% water vapor in the feed.