The electrochemical and physical properties of composite polymer electrolytes based on a blend of poly(methyl methacrylate) (PMMA) and poly(ethylene glycol diacrylate) (PEGDA) are investigated. The addition of nanometre-size TiO2 filler decreases the crystallinity of the polymer electrolytes and also improves the ionic conductivity and the interfacial resistance between the electrode and the electrolyte. In addition, this ceramic filler enhances the mechanical strength of the electrolytes. A prototype battery, which consists of a graphite anode, a LiCoO2 cathode, and the composite polymer electrolyte coated on a poly(propylene) (PP) separator, shows good cycling performance at high rate. (C) 2003 Elsevier B.V. All rights reserved.