Epitaxial Fe3O4(111) films were studied by scanning tunneling microscopy (STM). Atomic resolution STM images exhibit a hexagonal lattice of protrusions with a 6 Angstrom periodicity assigned to the topmost Fe cations. In contrast to the bias polarity-independent STM images obtained on the clean surface, the adsorbed species are imaged as protrusions at positive bias and as depressions at negative sample bias. They occupy the top and threefold hollow sites of the topmost Fe-layer, whereas no adsorbates are found on Fe vacancy sites, at step edges and on the surface domains that are FeO(111) in nature. The data were explained by assuming the dissociative water adsorption to occur on the regular Fe3O4(111) surface, which exposes both acidic Fe and basic O sites. The diffusion of adsorbed species was studied by consecutive STM images. Both translational and rotational moving of "dimer''-species was observed.