Polyaniline/nano-TiO2 composites with the content of nano-TiO2 varying from 6.2 wt % to 24.1 wt % were prepared by using solid-state synthesis method at room temperature. The structure and morphology of the composites were characterized by the Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UVvis) absorption spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic chargedischarge measurement, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results from FTIR and UVvis spectra showed that the composites displayed higher oxidation and doping degree than pure PANI. The XRD and morphological studies revealed that the inclusion of nano-TiO2 particles hampered the crystallization of PANI chains in composites, and the composites exhibited mixed particles from free PANI particles and the nano-TiO2 entrapped PANI particles. The galvanostatic chargedischarge measurements indicated that the PANI/nano-TiO2 composites had higher specific capacitances than PANI. The composite with 6.2 wt % TiO2 had the highest specific capacitance among the composites. The further electrochemical tests on the composite electrode with 6.2 wt % TiO2 showed that the composite displayed an ideal capacitive behavior and good rate ability. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012