Novel magnetic composites (Ni 0.5 Zn 0.5 Fe 2 O 4 –MWCNTs) of multi-walled carbon nanotubes (MWCNTs) coated with Ni 0.5 Zn 0.5 Fe 2 O 4 nanocrystals were synthesized by chemical precipitation–hydrothermal process. The composites were characterized by X-ray powder diffractometer (XRD), X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), etc. A temperature of about 200°C was identified to be an appropriate hydrothermal condition to obtain Ni 0.5 Zn 0.5 Fe 2 O 4 –MWCNTs, being lower than the synthesis temperature of a single-phase Ni 0.5 Zn 0.5 Fe 2 O 4 nanocrystals. The sizes of Ni 0.5 Zn 0.5 Fe 2 O 4 in the composites were smaller than those of Ni 0.5 Zn 0.5 Fe 2 O 4 nanocrystals in single phase. The composites exhibited more superparamagnetic than Ni 0.5 Zn 0.5 Fe 2 O 4 nanocrystals in their relaxation behaviors. The magnetic properties measured by a vibrating sample magnetometer showed that the composites had a high coercive field of 386.0Oe at room temperature, higher than those of MWCNT and Ni 0.5 Zn 0.5 Fe 2 O 4 nanocrystals.