Catalysts including multi-transition metal doped copper-cobalt spinel mixed oxide catalyst materials for direct NOx decomposition with selectivity to N2 from combustion engine exhaust, while minimizing formation of the N2O product. In one example, the catalyst may include a ternary zinc-doped copper-cobalt spinel material or a quaternary manganese+zinc doped copper-cobalt spinel material. The catalysts are effective for reducing NO to N2 at suitable temperatures of 350-500° C., with and without excess O2 presence.