A series of cerium-tungsten oxide catalysts was prepared by the co-precipitation method and was evaluated for the selective catalytic reduction of NOx by ammonia (NH3-SCR) over a wide temperature range. These catalysts were characterized by BET, XRD, XPS and H-2-TPR analyses. The experimental studies demonstrated that, among cerium-tungsten oxides, CeO2-WO3 with a Ce/W molar ratio of 3/2 exhibited the best activity toward NH3SCR reactions, N-2 selectivity and SO2 durability over a broad temperature range of 175-500 degrees C at a space velocity of 47,000 h(-1). The strong interaction between Ce and W could be the main factor leading to the high activity of the CeO2-WO3 mixed oxide catalyst.