Aims: In this study, humic acid (HA) removal by iron oxide magnetic nanoparticles (IOMNPs) was surveyed in aqueous solutions. Materials and Methods: Batch adsorption technique was used to determine kinetic and isotherm parameters. The effects of pH value, agitation rate, adsorbent dose, contact times and the adsorbate concentrations on the adsorption efficiency were studied as critical parameters. The IOMNPs was characterized by X-ray diffraction. Results: HA adsorption on the IOMNPs was fitted with Freundlich isotherm model and followed the pseudo-second-order kinetics. Results revealed that at HA concentration of 10 mg/L, pH 4.5, adsorbent dose of 2.7 g/L, agitation rate of 250 rpm and contact time of 90 min at presence of 0.1 M NaCl as an ionic strength agent, the HA removal reached to about 98%. Also, the turbidity of treated samples was increased with increasing of HA loading. Conclusions: With increasing HA concentrations, adsorption capacity of IOMNPs was increased and HA removal efficiency was decreased. By adding ionic strength, HA removal was improved and turbidity of treated samples was reduced.