Polymer electrolytes have become materials of considerable interest due to the wide range of their possible applications. However, their significantly low ionic conductivity at room temperature and their poor mechanical properties at temperatures above the crystalline-amorphous phase transition (around 65-degrees-C) considerably limit their usage. Introducing an inert "filler" into the polymer electrolyte as a means for increasing their mechanical and electrical properties, has been widely recognized. In this work we report the characteristics of (PEO)8LiClO4 + x weight % gamma-LiAlO2 with x = 0, 10, 20 and 30, by describing results obtained by nuclear magnetic resonance and conductivity studies.