The aim of this work consists in to incorporate organic compounds as PAMAM (Polyamidoamine) dendrimers into the polymeric Nation matrix to prepare composite membranes as a possible alternative to reduce methanol crossover effect. Composite Nation membranes were prepared using a 3 wt% of Generation-4 hydroxyl-terminated PAMAM (G4OH) dendrimers containing 64-terminal OH-functional groups. The influence of PAMAM-(G4OH) dendrimer on chemical-physical properties of the composite membrane was highlighted resulting in a reduction of the methanol permeability (1.05 x 10(-6) cm(2) s(-1)) if compared to a recast bare Nation membrane (8.19 x 10-6 cm(2) s(-1)), used as a reference. Good proton conductivity was also observed for PAMAM-(G4OH) composite membrane. The polarization curves carried out at 100 degrees C in the presence of 2 M methanol have revealed the higher performance of the PAMAM-(G4OH) membrane when compared to a recast Nation membrane. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.