Magnetic iron oxide nanoparticles were synthesized by co-precipitation method and characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), and scanning electron microscopy (SEM). Adsorption properties of the synthesized magnetic iron oxide nanoparticles towards iron ions were systematically investigated, including pH effect, adsorbent dosage, initial concentration, temperature, adsorption equilibrium and adsorption kinetics. The adsorption kinetics was studied by the pseudo first-order and pseudo second-order models. The adsorption isotherm for the removed iron ions were described by the Langmuir, Freundlich, D-R and Temkin isotherm models. The obtained results reveled that, the maximum adsorption capacity for Fe ions was 28.2mg/g and the removal percentage reached nearly 85% at adsorbent dosage 0.22g, temp. 600C, time 210min., pH 4 and initial concentration 117.3mg/L. The adsorption capacity was increased with the increase of temperature and decrease of adsorbent dosage. The reaction obeyed both the pseudo second-order model and Langmuir isotherm model (with correlating constant R2 is 0.98) . Also, the calculated mean free energy of the sorption from the Dubinin–Radushkevich isotherm was found to be 207.7KJ/Mol for iron ions, indicating a chemical sorption. With high regression coefficients for Fe ions at 302K, and thermodynamic calculations suggested that the adsorption of iron ions onto the magnetic iron oxide nanoparticles is an endothermic process.