A novel hyperbranched poly(glycidol) (HPG) was prepared and characterized. The synthesized HPG was used as a substrate of a polymer electrolyte. The ionic conductivity of a blend of HPG, polyurethane (PU), and salt was studied. The ionic conductivity of HPG/PU/LiClO4 was about 6.6 X 10(-6) S(.)cm(-1) at 20 degreesC and 6.3 X 10(-4) S(.)cm(-1) at 60 degreesC. The results indicated that HPG showed higher solubility for salt than linear polyether when both had the same [O]/[Li-] molar ratio. The main reason was that more cavities and a lower degree of chain entanglement in HPG resulted in a lower glass-transition temperature and were beneficial for decreasing the aggregation of salt or enhancing the ionic conductivity.