This Letter reports a novel PEO-based nanocomposite polymer electrolyte by using solid super acid SO42-/ZrO2 as filler. XRD, DSC, and FT-IR results prove the strong Lewis acid-base interactions between SO42-/ZrO2 and PEO chains. The addition of SO42-/ZrO2 can enhance the ionic conductivity and the lithium ion transference number of the electrolyte. The highest room temperature ionic conductivity of 2.1 x 10(-5) S cm(-1) is obtained for the sample PEO12-LiClO4-7%SO42-/ZrO2. The excellent performances such as good compatibility with lithium electrode, and broad electrochemical stability window suggest that PEO-LiClO4-SO42-/ZrO2 nanocomposite electrolyte can be used as electrolyte materials for lithium polymer batteries. (C) 2004 Elsevier B.V. All rights reserved.