A process for reducing the content of NO.sub.x and N.sub.2O in gases, in
particular in process gases and offgases, which comprises the measures:
a) addition of at least one nitrogen-containing reducing agent to the
NO.sub.x- and N.sub.2O-containing gas in at least the amount required for
complete reduction of the NO.sub.x; b) addition of a hydrocarbon, of
carbon monoxide, of hydrogen, or of a mixture of one or more of these
gases to the NO.sub.x- and N.sub.2O-containing gas for the reduction of
the N.sub.2O; and c) introduction of the gas mixture into at least one
reaction zone at temperatures of up to 450.degree. C., which contains one
or more iron-laden zeolites. The process can be used, in particular, in
nitric acid production, for offgases from power stations or for gas
turbines.