Poly(N-propane sulfonic acid aniline) (PSPAN) can be formed between the lamellas Of V2O5 xerogel by in situ oxidative polymerization/intercalation of N-propane sulfonic acid aniline in the presence of air (V2O5 being the oxidation agent). The PSPAN/V2O5 nano-composites were characterized by XRD, TEM, TGA, FTIR, UV-vis-NIR, and conductivity measurement. The results show that the V2O5 maintains lamellar structure, but its interlayer spacing has increased from 1.18 to 1.31 nm. The FTIR spectra indicate that there is interaction between negatively charged oxygen of the sulfonic group of PASPN and the vanadium ion in V2O5 matrix. The electrical conductivity of PSPAN/V2O5 nanocomposite reached the value of 1.2 x 10(-2) S/cm, which is 10(4) times higher than that of the V2O5 xerogel, and is 10(2) times more than that of the PSPAN. It was found that the aging in air facilitated the chain growth of PSPAN between the V2O5 lamellas, resulting in the increase of the electrical conductivity. (c) 2006 Wiley Periodicals, Inc.