Synthesis and characterization of new nanocomposites of vanadium pentoxide (V2O5) and a sulfonated, alkylated polyaniline derivative (poly(N-propane sulfonic acid aniline), PSPAN) are described. These nanocomposites were characterized using infrared spectroscopy, X-ray diffraction (XRD), X-ray absorption, and some electrochemical methods, including chronopotentiometry (i.e. charge–discharge curves), cyclic voltammetry, impedance, and electrochemical quartz crystal microbalance (EQCM). Results indicate the presence of the organic material between the layers of the inorganic matrix, where some sulfonic groups of the polymeric chain interact with the vanadium atom. EQCM experiments have shown that anions have a negligible participation in the charge compensation process during the oxide/polymer-reduction reactions in the nanocomposite. This phenomenon was attributed to the presence of the negatively charge sulfonic group. Results point to the possibility of using this polymeric material as cathode in secondary lithium batteries, because mainly Li+ would be involved in the charge compensation process, thus not leading to changes in the electrolyte composition. The cyclability of the nanocomposite is higher that the vanadium pentoxide due to the fact that there is not an important swelling process.