The electrodeposition and nano-silica incorporation were used together to prepare the novel composite dodecyltrimethoxysilane/SiO2 thin films from silane sol-gel system on aluminum substrate. The results showed that both the two techniques can improve the films formation and their protectiveness. The influences of the deposition potential and the silica content in silane solution were investigated. A "critical deposition potential" and a "critical silica content" were both observed, under which the obtained silane films had the highest protective properties. The enhancement in film thickness has been detected by these two techniques from the elemental depth profiles of silane films as measured by secondary-ion mass spectroscopy (SIMS). Current-time curves were on-line recorded on aluminum electrodes in silane solutions. As compared with that in blank solution, the current response was found to be larger in silica-contained precursor, probably suggesting that the silica particles participate in the film deposition. (c) 2006 Elsevier Ltd. All rights reserved.