A method of reducing the N.sub.2O content in gases is described. A selected zeolite catalyst is used in the method. This catalyst is present in the H form and/or contains exchanged iron and is characterized by the presence of nonlattice aluminum in addition to the lattice aluminum in a molar ratio of from 1:2 to 20:1.The method can be used in nitric acid production for reducing the N.sub.2O content of process gases or offgases.