Metallic magnesium can be reversibly deposited from ethereal solutions of magnesium−aluminum complex salts of the general structure Mg(AlCl4-nRn)2, where R = alkyl. In contrast to the case of lithium surfaces, already thoroughly investigated, the surface state of magnesium electrodes in contact with organic solutions is yet unclear. In this paper we report on a systematic surface analysis of magnesium electrodes in contact with various organic solutions, using XPS. We find in both clean tetrahydrofurane (THF) and THF solutions of dibutylmagnesium or butylmagnesium chloride that the metal surface consists of magnesium oxide and hydroxide (probably developed during manipulation and sample transfer); however, it does not develop thick passivation layers. In THF solutions containing Mg(AlEtBuCl2)2, surface residuals of carbon, aluminum, and chlorine are detected yet are restricted to the outermost part of the surface, as physically adsorbed species. From their concentration one deduces that both the complex s...