Magnesium (Mg) alloys for metal electroplating require a surface pretreatment, i.e., the removal of the spontaneously oxidized surface layer (MgO, Mg(OH)(2), and MgCO3). However, the use of highly toxic and/or corrosive acids in conventional pretreatment processes has become an issue. In this study, a facile and less toxic pretreatment is demonstrated and applied in aluminum (Al) electroplating. The immersion of the AZ31 Mg alloy into acetic anhydride (Ac2O) removed the spontaneously oxidized surface layer and formed a thin but stable magnesium acetate (Mg(OAc)(2)) layer that protects the metal substrate from further oxidation. The Al electroplating bath is a concentrated diglyme (G2)-AlCl3 organic solution that can readily dissolve Mg(OAc)(2) to enable direct plating onto a metal substrate. The as-deposited Al layer has a compact and crack-free morphology that improves the corrosion resistance and hardness (2.7 GPa). Owing to the lack of an interfacial oxidized layer, heat treatment led to the successful diffusion of Mg and Al atoms, which increased the hardness to 4.4 GPa. The Ac2O pretreatment of Mg alloys enables the successful Al electroplating and subsequent heat treatment.