The ionic conductivity of a hybrid polymer electrolyte was investigated as a function of temperature and salt concentration and compared to the corresponding liquid electrolyte. The hybrid polymer electrolyte was based on a radiation induced cross-linked polyether network with propylene carbonate in an interpenetrating liquid phase and LiAsF6 as electrolyte salt. The temperature behavior was best explained by the Vogel-Tamman-Fulcher relation. The activation energy was found to decrease with salt concentration, whereas the apparent glass-transition temperature increased. At 0.08 mol kg(-1) LiAsF6, the real glass-transition temperature was found to be 60 K higher than the apparent glass-transition temperature, but at 2.52 mol kg(-1) LiAsF6 no difference was found.