Three-dimensional macro/mesoporous Co3O4-CeO2 was prepared via a facile self-sustained decomposition of metal-organic complexes. Porous Co3O4-CeO2 was characterized using X-ray diffraction, scanning electron microscopy/transmission electron microscopy imaging, N-2 adsorption/desorption and X-ray photoelectron spectroscopy to examine the morphology and microstructure to find out the cause. Co3O4-CeO2 with the 3D hierarchical porous structure consisting of nanoparticles is a coral-like shape with a size of tens of micrometers and exhibits the hierarchically porous morphology, in which the walls of the macropores contain smaller mesopores. The catalytic performance of the porous Co3O4-CeO2 for CO oxidation has been studied. Among the obtained catalysts, the porous Co3O4-CeO2 with 20 wt% Co exhibits the best catalytic activity and the 50 % CO conversion can be reached at 74 A degrees C. The presence of transition metal element Co can promote the production of oxygen vacancies and improve oxygen mobility, which result in enhancing the oxygen-storage capacity of porous Co3O4-CeO2 and its catalytic performance for CO conversion. [GRAPHICS] .