An innovative electrolyte membrane concept based on the synergic combination of randomly porous doped PBI membranes 80% in porosity containing H-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as intrinsic proton conductor and microporous ETS-10 coatings as diffusional barriers has been developed for High Temperature PEMFC applications. The preparation route, involving up to 5 different steps, has been carefully optimized based on the evaluated proton conductivity and durability properties in presence of humidity at temperatures above 150 degrees C. The proton/methanol transport selectivity values of the optimized nanostructured membranes at 50 degrees, 100 degrees and 150 degrees C clearly outperform dense PBI and Nafion counterparts used as references. Moreover, the H-2 permeability values for both the optimized nanostructured electrolyte membrane and dense PBI are quite similar at the examined conditions; indicating the suitability of the preparation procedure in terms of fuel cross-over. Finally, the as prepared membranes have been validated in H-2/O-2 single cell under non humidified conditions up to 180 degrees C as a "proof of concept" demonstration. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.