Composite polymer electrolyte films consisting of poly(ethylene glycol) based thermoplastic polyurethane blended with poly(ethylene oxide) (denoted as TPU(PEG)/PEO) incorporating LiClO4–PC have been prepared and their electrochemical properties were studied. The thermal analysis of the composite films were performed to demonstrate the miscibility of the polymer blend by using differential scanning calorimeter (DSC). TPU(PEG)/PEO based polymer electrolyte shows ionic conductivity of the order 6.4×10−4 S/cm at room temperature, irrespective of time evolution. Cyclic voltammogram shows that this composite electrolyte has good electrochemical stability in the working voltage ranging from 2 to 4.5V. Cycling performances of Li/polymer electrolyte/LiCoO2 cells are also followed. From AC impedance results, the recharging ability of the cells is proved to be dominated by the passive layer formation at Li electrode–polymer electrolyte interface.