In this study, iron oxide nanoparticles (maghemite) were used to remove Ni (II) and Cr (VI) from mine’s waste water. First, by using novel single step, maghemite nanoparticles (?-Fe2O3) produced at room temperature, without the use of natural solvents and oxides. The average particle size of the maghemite was estimated to be 14 nm, by transition electron microscope (TEM(. Various factors influencing, such as initial concentration, pH, time and dose of nanoparticles at a constant temperature of 30 ° C, were studied. The results indicated that, adsorption reaction of Cr (VI) and Ni (II) to maghemite nanoparticles, equilibrium within 12 minutes. Absorption rate, decresed with increasing initial concentration and increased with increasing contact time, amount of adsorbent and temperature. best chromium absorb occurs at 50 mg/l initial concentrations, 0.15 gr doses of nanoparticles, 70 ?C and also pH=2.6 and best nickel absorb occurs at pH=8.5. Absorption isotherms were analyzed by Langmuir and freundlich models and It was found that the absorption of chromium and nickel on maghemite nanoparticles, follow Langmuir absorption model. . Based on the results, in the same situation, nickel adsorption is better than chromium adsorption. For recovery of adsorbent, hydrochloric acid (HCL) and NaOH with concentrations of 0 .05 M and 0.01 M, were used, respectively. Based on the results, in the same situation, nickel adsorption is better than chromium adsorption.