Molybdenum oxide based conversion coatings have been formed on the surface of the depleted uranium-0.75 wt.% titanium alloy. Electrochemical impedance spectroscopy (EIS) measurements have been performed on the as-made and aged coatings and compared with the untreated depleted uranium (DU) alloy. The Nyquist and Bode plots of the as-made coating were similar to the untreated samples and contained capacitive and inductive loops. The aged coating exhibits significantly different behavior from the as-made coating and has been modeled with a four element equivalent circuit that contains a constant phase element (CPE). (C) 2007 Elsevier Ltd. All rights reserved.