The invention relates to catalyst plates for reducing nitrogen oxide in exhaust gases. These plates are molded of granular Fe.sub.2 O.sub.3 catalyst material and a binder. To achieve high activity and strength in the plates, these are molded of a combination of a first mixture comprised of Fe.sub.2 O.sub.3 catalyst material and phosphoric acid as binder, and a second, separately-produced mixture comprised of Fe.sub.2 O.sub.3 catalyst material and sulphuric acid as binder. The plates can also be a molding having layers, which layers have alternate layers of the first and second mixtures.