Polypyrrole(PPy)/Zn 0.5 Cu 0.5 Fe 2 O 4 nanocomposite was prepared by a simple, general and inexpensive in situ polymerization of pyrrole in the presence of Zn 0.5 Cu 0.5 Fe 2 O 4 nanoparticles in w/o microemulsion. The effects of PPy coating on the magnetic properties of Zn 0.5 Cu 0.5 Fe 2 O 4 were investigated. By means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) technique, the microstructure and magnetic property of samples were characterized. The SEM analysis indicated that PPy was deposited on the porous surface of Zn 0.5 Cu 0.5 Fe 2 O 4 . The results were shown that the magnetic parameters such as saturation magnetization and coercivity of Zn 0.5 Cu 0.5 Fe 2 O 4 decreased upon PPy coating.