Hybrid materials based on Cs-PW particles (Cs3PW12O40) as the polyoxometalate were dispersed in CNTs matrices (multiwalled carbon nanotubes) with different oxidation degree. XRD, SEM. and EDS analyses confirmed the presence of Cs-PW particles in all hybrid materials, and revealed the influence of the CNTs oxidation degree on the dispersion of Cs-PW particles. Hybrids (CNT-S-50 and CNT-S-75) prepared with highly oxidized CNTs (CNT-S) showed the highest dispersion degree of Cs-PW (less segregation) with the best electrochemical behavior. The electrocatalytic properties were evaluated for the first time in the electroreduction of bromate ion, showing interesting results related with the concentration and dispersion degree of the hybrids components. (C) 2009 Elsevier Ltd. All rights reserved.