Method of selective catalytic purification of waste gases from nitrogen oxides

Method of selectively removing nitrogen oxides from waste gases by reducing said nitrogen oxides with ammonia, which comprises a waste gas containing nitrogen oxides in admixture with a substantially stoichiometric amount of gaseous ammonia through a catalyst at a temperature of 100.degree. - 500.degree. C, at a volumetric velocity of passage of 5000 - 100,000 hour and a volumetric ratio of the gaseous ammonia to nitrogen oxides of 0.7 - 1.5, said catalyst consisting essentially of a mixture of oxides of vanadium and manganese applied to an inert carrier said oxides being taken in a weight ratio of V.sub.2 O.sub.5 /Mn.sub.2 O.sub.3 of 0.1 - 30, the total content of said oxides of vanadium and manganese being 5-40 percent of the total weight of the catalyst, whereby substantially all of the nitrogen oxides are reduced to nitrogen and the waste gas is thus purified of nitrogen oxides.