The development of robust catalysts that oxidize water is necessary for their application in artificial photosynthesis cells. Here we report the synthesis and characterization of octahedral CoFe2O4 nanoparticles obtained through a novel aqueous method that employs betaine, (CH3)(3)+NCH2COO-, as the stabilizer agent. The synthetic conditions are modified changing the betaine content and the metal precursor ratios.These conditions modify the shape of CoFe2O4 finding both, octahedral and semi-spherical nanoparticles.Linear voltammetry measurements show the octahedral CoFe2O4 lead to an overpotential of similar to 390 mV at the onset potential for water oxidation at alkaline conditions. Among the as-synthesized cobalt-ferritenanomaterials, the CoFe(1:2)-C in the form of tiny nanoparticles performed a superior electrocatalytic water oxidation in alkaline conditions, showing an overpotential of similar to 335 mV, which is lower than other similar catalysts in literature. (C) 2017 Elsevier B.V. All rights reserved.