The invention involves the production of a catalyst that contains (1) at least one refractory inorganic oxide support, (2) at least one iron oxide, and (3) at least one cerium oxide, (4) at least one metal A, for example, from Groups VIB, VIIB, VIII, and IB of the Periodic System and, optionally (5) at least one compound of metal B, for example, from Groups IA, IIA, the rare-earths group, and Group IVB of the Periodic System, deposited in the form of a porous layer ("washcoat") on a ceramic or metal substrate:(a) atomizing an aqueous suspension of at least one powder of the refractory inorganic oxide, cerium salt, iron salt, and optionally salt of the metal B; and/or A(b) resuspending the resultant powder and adding any remainder or all of the compound of metal B, as well as, optionally at least one bonding agent and, optionally at least one mineral acid or organic acid;(c) coating a ceramic or metal substrate is coated with the suspension obtained in step (b);(d) calcining the resultant coated substrate;(e) impregnating the resultant coated and calcined substrate with any remainder or all of the precursor of metal A; and(f) thermally activating said coated, calcined, and impregnated substrate coming from step (e).