Abstract: The adsorption and thermal desorption of hydrogen on the surfaces of Sm overlayer and Sm/Ni alloys have been investigated with TDS and AES.The uptake of hydrogen on unannealed Sm overlayer is associated with a slow surface chemisorpton process.Thermal desorption spectra exhibited a broad feature at lower temperature of~400K and a weak band in the 500~600 region.The TD spectra of hydrogen from Sm/Ni surface alloy are significantly different from those observed on Ni surface.Post adsorption of oxygen onto a hydrogen preadsorbed Sm/Ni surface alloy leads to displace hydrogen into the vacuum rather than to drive it into the subsurface region.Preadsorption of oxygen completely suppresses any further uptake of hydrogen and induces a complicated profile of TD spectra of hydrogen from Sm/Ni alloy surfaces.