Polycrystalline mesoporous Co3O4 has been successfully fabricated using a simple but efficient controlled thermal decomposition approach and their catalytic activities for low temperature CO oxidation were evaluated. In such a synthesis, micrometer-sized polyhedral cobalt oxalate crystals were first prepared and used as precursor. Mesoporosity was then generated via the pyrolysis of the cobalt oxalate precursor and the resultant nano-sized Co3O4 crystallites connected together to form mesoporous structure within the original micrometer-sized particles. The as-prepared material by calcination at 300 degrees C at a heating rate of 0.5 degrees C/min possessed high surface area and showed extraordinarily high catalytic activity for low temperature CO oxidation, the full CO conversion can be achieved at as low as -70 degrees C. (C) 2011 Elsevier B.V. All rights reserved.