Abstract: Polymerization of aniline on a carbon nanotube/nanocrystalline TiO₂ (CNT/nanoTiO₂) film electrode was achieved in 0.5 mol/L sulfuric acid including 0.2　mol/L aniline at scanning voltage －0.1~0.9 Vand a scanning rate of 50 mV/s, and electrochemical properties and struture of carbon nanotube/nanocrystallineTiO₂) polyaniline (CNT/nanoTiO₂) PAn) complex film were characterized by cycl ic voltammetry, electrochemical impedance spectra (EIS) and SEM. The results show that the CNT/nanoTiO₂)-PAn complex film preparated has a loose，porous， nano-fibrous structure and a good electrical conductivity.

Key words: polyaniline, electrochemical polymerization, carbon nanotubes/nanocrystalline TiO₂ complex film, electrochemical impedance spectra