The existence of toxic metals in surface and waters, even at hint levels, poses a considerable danger to humans and the ecosystem. So, removal of heavy metals is an important process. In this study, an adsorbent made of magnetite nanoparticles (MNPs) was employed to remove chromium ions form aqueous solution. MNPs (before and after) were characterized by SEM, FT-IR and XRD techniques. These nanoparticles have a spherical shape and their diameter about 11 nm. A number of factors were studied including (concentration, pH, time, sorbent dose and temperature). Thermodynamics, kinetics and adsorption isotherms of MNPs were all investigated. This adsorption describes as a spontaneous process, endothermic and pseudo-second order kinetics. The adsorption isotherm was described by the Temkin model.