Micro- and nanostructured electrode interfaces have the potential to exhibit improved performance characteristics. Here, we illustrate the interaction of an electropolymerised polyaniline film with silica microparticles on glassy carbon electrodes. It was found that the polyaniline grew preferentially around the silica particles rather than on the underlying electrode surface. This was found to be due to the adsorption of aniline monomers onto the silica surface, followed by in situ electropolymerisation. The thickness of the PANI layer could be controlled through the adjustment of polymerisation time from several to many tens of nanometres. In conjunction with immobilisation of the enzyme, horseradish peroxidase (HRP), the electrocatalytic reduction of hydrogen peroxide was found to be enhanced under certain conditions over polymer films grown in the absence of silica particles. It is believed that this may be due to the special structure of the silica-PANI core-shell particles. Silica particles coated with a nanofilm of PANI appear to adsorb HRP more effectively, while also increasing the active electrode surface area. (c) 2006 Elsevier Ltd. All rights reserved.