Abstract: Polyanilinemanganese dioxide nanocomposites (PANI-MnO2) were prepared by a chemical oxidative polymerization. MnO2 nanorods were synthesized by a hydrothermal reaction and then modified with cetyltrimethylammonium bromide（CTAB）before the polymerization. PANI-MnO2 nanocomposites were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), thermogravimetric (TG) analysis, cyclic voltammetry (CV) and galvanostatic chargedischarge. Results show that MnO2 nanorods and polyaniline nanowires interpenetrate to form network structures. The specific capacitance of composite electrode varies with the amount of MnO2 and the maximum is 104 F/g when the mass ratio of An to MnO2 is 1∶3 at a current density of 1 mA/cm2. The electrochemical performance of MnO2 electrode is significantly improved by the introduction of polyaniline.