Scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy have been used to characterize the surface of depleted uranium molybdenum (DU-Mo) alloys as a chemical surrogate to determine potential challenges with the surfaces of manufactured and stored U-Mo foils and powders. Even when stored and shipped in an inert atmosphere, U-Mo has a tenacious surface contamination of oxygen and carbon. The 8 at. % molybdenum (DU-8Mo) powder and 10 at. % molybdenum (DU-10Mo) foil samples have surface contamination of oxygen and carbon in different ratios that is hundreds to thousands of nanometers thick. The DU-8Mo powder sample has been stored in an inert atmosphere and as a result has a lower carbon-to-oxygen ratio at the surface than the DU-10Mo foil sample that was stored in air. This surface contamination has not been removed by up to 20 min of argon ion sputtering nor with 5% hydrogen in argon heat treatment for up to 96 h at 950°C.