Mesoporous γ-Fe 2 O 3 /SiO 2 nanocomposite containing 30mol% of γ-Fe 2 O 3 was prepared by a template-free sol–gel method, and its removal ability for methyl orange (MO) was investigated. The nanocomposite was characterized using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared (FTIR) absorption measurements, nitrogen adsorption–desorption measurements, and magnetic measurements. The synthesized γ-Fe 2 O 3 /SiO 2 nanocomposite has a mesoporous structure with an average pore size of 3.5nm and a specific surface area of 245m 2 /g, and it exhibits ferrimagnetic characteristics with the maximum saturation magnetization of 20.9emu/g. The adsorption of MO on the nanocomposite reaches the maximum adsorbed percentage of ca. 80% within a few minutes, showing that most of MO can be removed in a short time. The MO adsorption data fit well with both Langmuir and Freundlich adsorption isotherms. The maximum adsorption capacity of MO is estimated to be 476mg/g.