Solid polymer electrolyte films based on poly (ethylene oxide) (PEO) complexed with sodium nitrate (NaNO3) have been prepared by a solution-cast technique. The complexation of NaNO3 salt with PEO has been confirmed by X-ray diffraction, infrared (IR) and optical microscopic studies. Measurements of the de conductivity in the temperature range 303 to 373 K and the transference numbers have been carried out to investigate the charge transport in this polymer electrolyte system. Transport number data show that the charge transport in this polymer electrolyte system is predominantly due to ions. Using the polymer electrolyte, solid-state electrochemical cells have been fabricated. The various cell parameters are evaluated and reported.