A new type of composite gel polymer electrolyte(CGPE) with a blend of polyethylene glycol 200 maleate, methyl methacrylate(MMA) and poly(methyl methacrylate)(PMMA) coated and polymerized on the microporous polyolefin membrane was prepared by means of ultra-violet crosslinking and then soaked in a lithium salt solution. The chemical construction, morphology, ionic conductivity of composite gel polymer electrolytes, and their interfacial stability between lithium metal electrode were characterized by using infrared spectroscopy, H-1 NMR measurement, scanning electron microscopy, alternating current impedance and linear sweep voltammetry, respectively. The ionic conductivity of the CGPE reaches 10(-3) S/cm at room temperature and its electrochemical stability window is 4.7 V, which makes it a potential candidate for application as polymer electrolyte in devices. (c) 2005 Elsevier B.V. All rights reserved.