The polymer electrolyte PEO + AgNO3 has been investigated by IR, optical absorption, DTA, electrical conductivity, mobility, and transport number measurements. The material is a mixed (ionic + electronic) conductor. The ionic conductivity is due to Ag+ and anionic movement. The material properties change with time, mainly associated with an increased electronic conductivity due to reduction of Ag+ in PEO lattice. The maximum electrical conductivity has been found to be approximate to 3 X 10(-7) s cm(-1) for the composition Ag+/EO=0.014 to 0.085.