Indium is one of the contaminants of the optoelectronics industry, and adsorption is a potential treatment method for this pollutant A magnetic adsorbent manufactured from magnetite (Fe3O4) can be easily recovered from treated water by magnetic force without requiring further downstream treatment. In this research, the surface of magnetite is modified with oleic acid, methyl methacrylate and ethylenediamine (EDA/MMA/OA/Fe3O4). A magnetic adsorbent (EDA/MMA/OA/Fe3O4) made by magnetite modified with oleic acid, methyl methacrylate and ethylenediamine was used to adsorb indium ions solution in a batch system. The indium ions adsorption behavior by EDA/MMA/OA/Fe3O4 was in good agreement with both the Langmuir and Freundlich adsorption isotherm. The maximum adsorption capacity (q(m)) and Gibbs free energy of indium ions at 298 K was 54.18 mg g(-1) and -17.94 kJ mol(-1), respectively. A pseudo-second-order model could best describe the adsorption kinetics, and the derived activation energy was 5.96 kJ mol(-1). The optimal condition of indium ions desorption from EDA/MMA/OA/Fe3O4 was provided by 0.01 M HNO3 in aqueous solution. (C) 2015 Elsevier B.V. All rights reserved.