Co3O4 nanomaterials were synthesized by hydrothermal method and were applied for low temperature CO oxidation and methane combustion. The addition of ethylene glycol and its concentration significantly influenced the size and shape of the Co3O4 oxides. Nanosheets of Co3O4 were synthesized in ethylene glycol solution and nanospheres were formed in water. The activity of oxygen species in the nanosheets and nanospheres were characterized by hydrogen/methane programmed reduction, oxygen programmed desorption and XPS. The results showed that the Co3O4 nanosheets exhibited more active oxygen species than the Co3O4 nanospheres, leading to the higher activity in the oxidative reactions. The study demonstrated the importance of active oxygen species in Co3O4 catalysts to achieve high catalytic performance towards the carbon monoxide and methane elimination at low temperatures. (C) 2017 Elsevier Ltd. All rights reserved.