Enthalpy of activation for proton exchange processes in fully hydrated hybrid sulfonated poly( ether ether ketone)-silica (SPEEK/SiO2) membranes were measured from the H-1 NMR spectra under magic angle sample spinning (MAS). For the first time Eyring function is used for this purpose. Two exchange processes between different water pools were detected. The isotropic chemical shift of the H-1 spectrum allows us to obtain information about the normalized enthalpy of activation characterizing the water exchange. These results show that the proton exchange membranes performances could be improved by addition of small concentrations of silica in the range of 5-10 wt.%. (c) 2008 Elsevier B. V. All rights reserved.