The study deals with the electrochemical and physico-chemical characterizations of new proton-conducting ionic liquids. Through the use of several amines and perfluorinated acids, it attempts to define the most appropriate ionic liquids for use in high temperature PEMFCs. In addition to the usual characterizations based on Pulsed Field Gradient NMR and conductivity measurements, NMR correlation techniques NOESY, HOESY and COSY experiments are used to characterize the interactions and spatial proximities of ionic liquid species. (c) 2007 Published by Elsevier Ltd.