Abstract <p>Using the Pechini method, LaFe_{1 <i>– x</i>}Ni_<i>x</i>O₃ (<i>x</i> = 0, 0.6, 1) perovskite-containing catalysts supported on a monolith corundum support were prepared and studied in the reaction of high-temperature decomposition of nitrous oxide. It is shown that the supported catalysts can be arranged in the following order by activity: LaFeO₃/α-Al₂O₃ &gt; LaFe_0.4Ni_0.6O₃/α-Al₂O₃ &gt; LaNiO₃/α-Al₂O₃, which differs from the activity order of perovskites without a support. The change in the activity order is due to the interaction of the impregnating solution with the support, as a result of which an admixture of the nickel aluminate phase, inactive in this reaction, can be formed in nickel-containing catalysts. The LaFeO₃/α-Al₂O₃ catalyst with an active component content of ~5%, even with a fragment height of 20 mm (and a contact time of 0.06 s), provides a high (~84%) conversion of nitrous oxide, due to the possible presence of an impurity of the dispersed phase of active Fe₂O₃ as well.</p>