Three-dimensional (3D) manganese oxides consisted of tetragonal phase Mn3O4 and alpha-MnO2 with different morphology have been directly grown vertically on Ti foil by a simple electrochemical method without any template and used as the catalysts for oxygen evolution reaction (OER). The results show that manganese oxides with different morphology show high activity and good stability for OER and the manganese oxide (MnOx) nanowire arrays obtained at 70 degrees C show higher activity and better stability than MnO with cotton wool structure and MnOx nanosheet arrays. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.