Using electrostatic layer-by-layer self-assembly, ultrathin films consisting of layer-pairs of oppositely charged poly(ethylenimine) and tungstoborate were grown onto quartz substrate or glassy carbon electrode. The multilayers were characterized by UV-vis absorption spectroscopy, cyclic voltammetry, and atomic force microscopy. Cyclic voltammetry indicates that the electrochemical properties of the polyoxometalate clusters are maintained in the multilayer films. Moreover, electron transfer to Fe(CN)(6)(3-/4-) electrochemically active probe molecules was also investigated by cyclic voltammetry. (c) 2005 Elsevier B.V. All rights reserved.