A polyoxometalates (POM) of Kegging-type structure, Cs3HPMo11VO40 has been tested as mesoporous matrix to increase Pt electrocatalytic activity, by the enhancement of particles dispersion and active area. Physicochemical characterization has been carried out to clarify the structural properties of the matrix. SEM micrograph demonstrated a big change of the morphological features identifying POMs crystals with diameter less than 500 nm. The composite catalyst has been prepared by mixing the polyoxometalates with Pt/Vulcan XC72-R catalyst. By RRDE studies, an improvement in catalytic activity has been observed, both for HOR and ORR, for the layer modified with polyoxometalate matrix. Carbon monoxide adsorption/desorption processes have been also studied in order to evaluate any possible effect towards CO poisoning. Finally, the behavior of a fuel cell, prepared with a POM-modified cathode, was evaluated at 100% relative humidity, revealing that a lower Pt loading can be applied in presence of POM co-catalyst, yielding uncompromised and durable performance. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.