Abstract: A catalyst for the purification of an exhaust gas by the removal, through selective reduction, of nitrogen oxides present in the exhaust gas, which comprises (A) 80 to 95% by weight of a sulfur oxide-containing catalytic oxide obtained by thermally treating at least one hydrous oxide compound selected from the group consisting of binary hydrous oxide compound of titanium and silicon, binary hydrous oxide compound of titanium and zirconium and ternary hydrous oxide compound of titanium, zirconium and silicon in the presence of at least one sulfur compound selected from the group consisting of sulfuric acid and ammonium sulfate, (B) 0 to 5% by weight of a catalytic oxide comprising vanadium oxide, (C) 1 to 15% by weight of a catlytic oxide comprising the oxide of at least one metal selected form the group consisitng of tungsten, molybdenum, tin and cerium.