Adsorption and desorption of D2O or H2O, as a simulator of HTO, on iron surface covered with thin iron oxide film were studied by thermal desorption (TD), electron stimulated desorption (ESD), photon stimulated desorption (PSD), X-ray photoemission spectroscopy (XPS), and scanning electron microscopy (SEM). When the iron was heated under constant heating rate (5K/min), adsorbed D2O was desorbed around 400K and 600K. Adsorbed D2O which could not be desorbed by heating to 773K could be desorbed by irradiation with photon or bombardment with electron.