Nanostructured SnO 2 was prepared by the sol–gel method. Aniline monomer was polymerized in the suspension of nanocrystalline SnO 2 to form inorganic–organic composite materials, in which SnO 2 nanoparticles were embedded within netlike polyaniline (PANI). Structural and morphological characterizations of SnO 2 and PANI/SnO 2 were carried out using power X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Their electrochemical properties were also investigated using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The as-prepared composites had excellent properties in the capacitance, and its specific capacitance was up to 305.3Fg −1 with a specific energy density of 42.4Whkg −1 and a coulombic efficiency of 96%. The results indicated that the PANI/SnO 2 had a synergistic effect of the complementary properties of both components.