A new solid polymer electrolyte based on semi-interpenetrating polymer networks (semi-IPN) of crosslinked poly(glycidyl methacrylate-co-acrylortitrile)/poly(ethylene oxide) (P(GMA-co-AN)/PEO) was synthesized with diethylenetriamine (DETA) as the crosslinking agent and characterized. Fourier transform infrared spectroscopy (FTIR) spectra suggested the formation of semi-IPN structure by crosslinking and revealed the interactions of Li+ ions with both the ether oxygen in PEO chain and the nitrogen atom in AN segments. Differential scanning calorimetry (DSC) and X-ray diffraction pattern (XRD) measurements showed that crystallization of the semi-IPN polymer electrolyte was greatly impeded. Measurement of mechanical properties revealed that tensile strength of the polymer electrolyte was increased after crosslinking. Results of electrochemistry tests suggested that the new polymer electrolyte exhibited a high-ionic conductivity (10(-4) S/cm) at room temperature, and an Arrhenius-like behavior of the conductivity was observed. And the semi-IPN polymer electrolyte with less content of PEO exhibited lower ion conductivity. (C) 2008 Wiley Periodicals, Inc.