In the present work, the electrical and thermal characterization of polymer electrolytes based on PEO/CF3COONa are reported, which turn out to be good ionic conductors near room temperature (of the order 10—4 Ω—1 cm—1 for high salt concentrations). The variation of conductivity with temperature (plotted as ln σ versus 1/T) and salt concentration suggests a complex formation. This is confirmed by differential scanning calorimetry (DSC), which also indicates that the blends are thermally stable up to approximately 480 K. The high conductivity and the single-phase behavior of the blends are explained in terms of the plastification effect of the organic salt on the PEO.