Abstract: A catalyst for the deep oxidation of organic compounds and carbon monoxide contains 2.7-11.5 mass. % of manganese (with respect to elementary manganese), balance alumina. Manganese stays as non-stoichiometric manganese oxide .beta.-Mn.sub.3 O.sub.4+x, where 0.1.ltoreq..times..ltoreq.0.25, containing 80-95% of all manganese atoms, and as manganese aluminate containing 20-5% of manganese atoms. Alumina in the active component is presented by the high temperature forms .alpha.-Al.sub.2 O.sub.3 (72-95 catalyst mass. %) and (.delta.+.theta.)-Al.sub.3 O.sub.3 (28-05 catalyst mass. %). The catalyst active component has a monolith defect structure, particles size being 50-70 .ANG.. Catalyst phase composition and structure form during its thermal treatment at 900.degree.-1000.degree. C.