Using a chemically induced transition in an FeCl 2 solution, γ-Fe 2 O 3 nanoparticles can be prepared from an amorphous precursor composed of FeOOH and Mg (OH) 2 . Surface modification by adding ZnCl 2 during liquid-phase synthesis was attempted. The magnetization, morphology, crystal structure, and chemical species of as-prepared samples were characterized by vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray energy-dispersive spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the surface of the γ-Fe 2 O 3 nanoparticles can be modified by adding ZnCl 2 to form composite nanoparticles with a γ-Fe 2 O 3 /ZnFe 2 O 4 ferrite core coated with Zn (OH) 2 and absorbed FeCl 3 6H 2 O; this modification can be enhanced by additional NaOH.