AbstractAdsorption and desorption of water on thin films of iron oxide formed on the iron surface were studied by AFM and X-ray photoemission spectroscopy (XPS). The morphological change of iron oxide or water droplets on the surface of iron oxide were observed by AFM. Electronic state of O 1s was observed by XPS after a sample was exposed to distilled water. Several peaks appeared and assignment to oxygen-containing surface species was discussed.