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The influence of catalyst pre-treatment temperature (650 and 750°C) and oxygen concentration (λ=8 and 1) on the light-off temperature of methane combustion has been investigated over two composite oxides, Co₃O₄/CeO₂ and Co₃O₄/CeO₂–ZrO₂ containing 30wt.% of Co₃O₄. The catalytic materials prepared by the co-precipitation method were calcined at 650°C for 5h (fresh samples); a portion of them was further treated at 750°C for 7h, in a furnace in static air (aged samples). Tests of methane combustion were carried out on fresh and aged catalysts at two different WHSV values (12000 and 60000mLg⁻¹h⁻¹). The catalytic performance of Co₃O₄/CeO₂ and Co₃O₄/CeO₂–ZrO₂ were compared with those of two pure Co₃O₄ oxides, a sample obtained by the precipitation method and a commercial reference. Characterization studies by X-ray diffraction (XRD), BET and temperature-programmed reduction (TPR …