This work describes the water oxidation reaction by the spinel Co3O4 nanopowder treated with coordinating organic compounds. Treatment of Co3O4 led to an increase in the Co3+ species at the oxide surface, probably due to stabilization by the adsorbed organic compounds, as well as partial oxidation of Co2+ to Co3+ ions by oxygen from air. Oxygen evolution reaction (OER) tests were carried out against the sacrificial oxidant cerium-(IV) ammonium nitrate (CAN), and higher TOF values were obtained for the treated samples in relation to the pure oxide, showing an influence of the Co3+/Co2+ ratio in the catalytic activity. The catalysts could be recycled up to five times without considerable loss of activity.