Polymeric electrolytes consisting of poly(ethylene oxide)-grafted polymethacrylates, lithium salts and ceramic filler (LiAlO2) have been prepared. The addition of a small amount of LiAlO2 increased the ionic conductivity of the polymeric electrolyte system containing LiClO4 salt over an ambient temperature range. Conductivity of 3.5×10−5 S cm−1 at 333 K (60°C) was obtained for the composite without any low molecular weight liquid component. The addition of the ceramic filler scarcely influenced the thermal properties of the polymeric electrolyte. XRD and 7Li NMR experiments showed that the ionic mobility can be enhanced in the composites by adding LiAlO2. For the polymeric electrolyte system containing LiCF3SO3 salt, however, the addition of the ceramic filler showed little influence on the ionic conductivity.