In this study, highly ordered mesoporous Co3O4 inverse opals are synthesized using polystyrene beads as a hard template, followed by a calcination in air. The morphology and crystalline structure of the mesoporous Co3O4 are investigated by scanning electron microscopy and X–ray diffraction techniques. The characterizations reveal that the thickness of the pore walls of the inverse opals is in the range of a few to a few tens of nanometers, the average diameter of the pores is in the range of 260 – 300 nm, and the mesoporous Co3O4 has a spinel crystalline structure. The electrocatalytic properties of the materials are investigated by the oxygen evolution reaction. The results show a superior activity of the mesoporous structure with a small Tafel slope and a low overpotential in the alkaline medium compared to the nanoparticle counterpart.