Nanocomposite hybrid materials (NHM) based on the immobilization and dispersion of SiW12 polyanion (H4SiW12O40) on a highly oxidized multiwalled carbon nanobue matrix (NTS) are presented. The synthesis procedure followed is designed in order to increase the SiW12 particles concentration on the NHM. XRD, FTIR, N2 adsorption isotherms, EDS, SEM, TEM, and cyclic voltammetry confirmed the presence of SiW12 nanoparticles, whose microstructure and dispersion characteristics were correlated with their BET surface area and their electrochemical behavior. Based on these studies, SiW12 nanoparticles are successfully nanodispersed in the highly oxidized carbon nanotube matrix (NTS), obtaining the highest SiW12 concentration and best electrochemical behavior for sample MH3. The electrocatalytic properties are evaluated for this optimized hybrid (MH3) in the electroreduction of bromated ion with good results.