The activation processes of [Cu-II(bdmpza)(2)] in the water oxidation reaction were investigated using cyclic voltammetry and chronoamperometry. Two different paths wherein CuO is formed were distinguished. [Cu-II (bdmpza)(2)] can be oxidized at high potentials to form CuO, which was observed by a slight increase in catalytic current over time. When [Cu-II(bdmpza)(2)] is initially reduced at low potentials, a more active water oxidation catalyst is generated, yielding high catalytic currents from the moment a sufficient potential is applied. This work highlights the importance of catalyst pre-treatment and the choice of the experimental conditions in water oxidation catalysis using copper complexes. (C) 2016 Published by Elsevier B.V.