This paper presents the main results obtained during the European project (FCH-JU) "LoLiPEM - Long-life PEM-FCH & CHP systems". The paper describes significant improvements in the polymer electrolyte by tailored heat treatments for cross-linking of Sulfonated Poly(ether ether ketone) (SPEEK), obtained without any addition of cross-linker species. The reported properties of the ionomers include mechanical properties, gas permeability and ionic conductivity. Innovative gas-diffusion electrodes are fabricated by the electrochemical deposition of Pt catalyst; the fuel cell current voltage characteristics are reported with Nafion and SPEEK-based binder. The fuel cell performances at 80 degrees C of membrane-electrode-assemblies containing a SPEEK membrane with a cross-linking degree of 32% are among the best in the literature compared with the PEMFC using membrane alternative than Nafion. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.