Compound poly(methylmethacrylate (MMA)-acrylic acid (AA)-ethyl acrylate (EA))/Fe3O4 superparamagnetic nanoparticles were synthesized successfully by emulsion polymerization and solvothermal reaction methods. The nanoparticles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD) and thermogravimetry analysis (TGA). P(MMA-AA-EA)/Fe3O4 nanoparticles exhibited superparamagnetic properties with a saturation magnetization value of 20 emu/g. The selective adsorption behaviors of nanoparticles toward dyes were investigated and the function of electronic interaction during the adsorption process was also discussed. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.