Ion conducting polymer electrolyte films having high salt concentrations have been studied. The system studied is PEO : NH(4)l, dispersed with alpha-Al2O3. Mechanically stable films with NH4+/EO ratio greater than or equal to 0.13 have been obtained by dispersal of Al2O3. The films have been characterized using various techniques such as X-ray diffraction (XRD), differential thermal analysis (DTA), polarization and complex impedance spectroscopy. Intercorrelation between polymer matrix crystallite size, conductivity, and alpha-Al2O3 particle size is established.