Heteropolyacid-doped conductive polymer coatings were grown by vapour transport of monomer (pyrrole or N-methylpyrrole) onto carbon paper coated with aqueous oxidant solutions (heteropolyacids or iron(III) chloride). Coated electrodes were studied by scanning electron microscopy and cyclic voltammetry. Polymer/heteropolyanion coatings had smooth morphologies giving pseudocapacitance of up to 422 F g (-1) (with respect to active polymer material) and 0.45 F cm (- 2) (geometric area of the electrode). (C) 2003 Elsevier Science Ltd. All rights reserved.