The surface chemistry on AZ31 and AZ91 magnesium alloys was characterized by X-ray photoelectron spectroscopy (XPS) in the corrosion and the passivation zones. In the corrosion zone, the presence of Mg(OH)(2) and MgCO3 species was found in the outer surface, whereas, in the inner layer, the co-existence of Mg(OH)(2), MgO and MgCO3 species was observed for both alloys. The presence of Al3+ in the surface electrolyte to form Al2O3/Al(OH)(3) and the formation of carbonate product provide a better passivation on the surfaces and retard the chloride-induced corrosion on the materials in the passivation zone. (C) 2010 Elsevier B. V. All rights reserved.