Thin oxide films were prepared electrochemically on the aluminum surface using the high-voltage discharge and potentiostatic methods in deionized water as an electrolyte. The growth of continuous films occurred only at potentials lower than the breakdown potential. The films obtained by the discharge method are more uniform and can grow to a higher thickness in comparison to those formed by the potentiostatic mode, as demonstrated by electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), and scanning Kelvin probe force microscopy (SKPFM). The data herein obtained can be used as a reference to understand better the properties of the films produced in conventional electrolytes where apart from water other species are present. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: [email protected]. All rights reserved.