An Mg(OH)(2)/carbon composite film was prepared on magnesium alloy AZ31 by an ascorbic acid (AA)-assisted hydrothermal method. All films were composed of crystalline brucite type Mg(OH)(2). Film thickness decreased with an increase in the amount of AA added. X-ray photoelectron spectroscopy studies revealed that a peak component related to sp(2)-hybridized carbons contributed to improve film conductivity. Film resistivity decreased with an increase in C content. The film obtained from the aqueous solution containing 10 g/L of AA showed the lowest corrosion current density of all samples. (C) 2015 The Electrochemical Society. All rights reserved.