Chemical anchoring of silica nanoparticles onto polyaniline (PANI) chains was conducted through electro-co-polymerization of aniline and N-substituted aniline grafted on surfaces of silica nanoparticles. The grafting of N-substituted aniline on surfaces of silica nanoparticles were realized through hydrolysis of triethoxysilylmethyl N-substituted aniline (ND42) and the following condensation reaction with silanol groups On surfaces of SiO2. Organic-inorganic interactions between PANI and SiO2 involved in electro-co-polymerization process pushed the polymer chains apart and so facilitated the ID growth of the polymer. Hence, the obtained hybrid film PANI/ND42-SiO2 displayed nano-fibrous morphologies (ca. 50 nm in diameter). Consequently, PANI/ND42-SiO2 exhibited an average specific capacitance of 380 Fg(-1), ca. 40% higher than that of PANI/SiO2 (276 Fg(-1)). The hybrid film also showed improved cyclic stability. (C) 2008 Elsevier Ltd. All rights reserved.