The crown-shaped molybdenum polyoxometalate cluster Na-26[{Na(H2O)(2)}(6){(mu(3)-OH)(4)(Mo20Mo34O164)-Mo-V-O-VI(mu(3)-CH3COO )(4)}].120H(2)O (Mo-54) was synthesized and first used as a bulk modifier to fabricate a three-dimensional modified WIGE electrode by the layer-by-layer method. The (Mo-54/PAH)(n) multilayer films have been characterized by X-ray photoetectron spectra (XPS) and atomic force microscopy (AFM). UV-vis measurements reveal regular film growth with each Mo-54 adsorption. The electrochemical method was used to characterize the modified WIGE electrode, which is important for practical applications. (C) 2004 Elsevier Inc. All rights reserved.