Lithium polymer composite electrolytes, formed by a blend of poly(ethylene oxide) (PEO), LiCF3SO3 lithium salt and a selected, nanoparticle ceramic filler, were prepared by hot-pressing through a solvent-free procedure. These dry, ionically conducting membranes were characterized in terms of ionic conductivity in the 30–105°C temperature range. The influences of several parameters such as the temperature, PEO molecular mass, the EO/Li molar ratio, and the nature and the content of ceramic filler were carefully evaluated.