Hybrid multilayer films were prepared by alternately depositing cationic dye methyl green (MG) and anionic sandwich-type polyoxometalate K-10[Co-4(H2O)(2)(PW9O34)(2)] (Co(PW9)(2)) via electrostatic layer-by-layer (LbL) self-assembly method. Film build-up was monitored by UV-vis spectroscopy which showed a regular stepwise growth. X-ray photoelectron spectroscopy data confirmed the successful fabrication of the hybrid films with MG-Co(PW9)(2) composition and scanning electron microscopy images revealed a completely covered surface with a non-uniform distribution of the molecular species. Electrochemical characterization of films by cyclic voltammetry revealed two tungsten-based reduction processes in the potential range between -0.9 and -0.5 V due to W-VI -> W-V in Co(PW9)(2). Studies with the redox probes, [Fe(CN)(6)](3-/4-) and [Ru(NH3)(6)](3+/2+), revealed that not only the electrostatic attractions or repulsions have effects on the kinetics of the probe reactions, but also the film thickness. Additionally, the {MG/Co(PW9)(2)}(n) multilayer films exhibit efficient W-based electrocatalytic activity towards reduction of nitrite and iodate. (C) 2015 Elsevier B.V. All rights reserved.