The nanocomposites of the polyaniline and Co1-xCuxFe2O4 (PANI/CoCuFe) were prepared by in-situ oxidative polymerization of aniline. Prepared nanocomposites samples were characterized by using various experimental techniques like X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM), Mossbauer spectroscopy and ultraviolet-visible spectrophotometty (UV-VIS). The elemental analysis as obtained from the energy dispersive X-ray spectroscopy (EDAX) measurement is in close agreement with the expected composition from the stoichiometry of the reactant solutions. XRD result confirms that all the samples have the single phase cubic spinet structure. Unit cell parameter 'a' is found to decrease with the increase in copper ion substitution. The crystallite size was investigated by using the Debye-Scherer formula and it was found in the range of similar to 28-37 nm. FE-SEM confirmed the homogeneous and well defined surface morphology of the synthesized samples. Fr-IR study showed the main absorption bands corresponding to the spinet structure those arose due to the tetrahedral and octahedral stretching vibrations. Cation distribution was estimated using XRD data. Hysteresis measurements revealed that the saturation magnetization decreased with increase in Cu2+ substitution. Magnetic environment of Fe-57 in Cu-doped cobalt ferrite was investigated by using Mossbauer spectroscopy. Mossbauer study evidenced the ferrimagnetic behavior of the synthesized samples. (C) 2013 Elsevier B.V. All rights reserved.