A new poly(propylene carbonate)/poly(ethylene oxide) (PEO/PPC) polymer electrolytes (PEs) have been developed by solution-casting technique using biodegradable PPC and PEO. The morphology, structure, and thermal properties of the PEO/PPC polymer electrolytes were investigated by scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry methods. The ionic conductivity and the electrochemical stability window of the PEO/PPC polymer electrolytes were also measured. The results showed that the T-g, and the crystallinity of PEO decrease, and consequently, the ionic conductivity increases because of the addition of amorphous PPC. The PEO/50%PPC/10%LiClO4 polymer electrolyte possesses good properties such as 6.83 x 10(-5) S cm(-1) of ionic conductivity at room temperature and 4.5 V of the electrochemical stability window. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 2718-2722, 2010