Poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene oxide (GO) decorated with Pt nanoparticles (PtNPs) was obtained and investigated. This hybrid nanocomposite material was morphologically characterized by several instrumental techniques like high-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD). Good coverage of crystalline Pt nanoparticles was achieved, the average diameter being 2 nm, meanwhile in the absence of polyelectrolyte the average diameter increased up to 4 nm. The electrocatalytic properties of this hybrid nanocomposite against H2O2 and methanol were ascertained by cyclic voltammetry. A modified glassy carbon electrode (GC) was able to reduce H2O2 at positive potentials (starting from similar to 150 mV vs. Ag/AgCl) meanwhile for methanol the ratio of the forward anodic peak current (I-f) to the reverse anodic peak current (I-b) was 1.42, indicating good tolerance of the catalyst towards the intermediate carbonaceous species accumulated on the electrode surface. (C) 2014 Elsevier B.V. All rights reserved.