A series of polyurethanes (PUS) with different polyether soft segments [polydioxolane (PDXL), polyethylene glycol (PEG), or PDXL/PEG] were synthesized successfully, and solid polymer electrolytes based on PU/LiClO4 complexes were prepared. The relations between structure and the ionic conductive properties of the PU-based electrolytes were investigated by means of Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and complex impedance analysis. Results showed that the glass-transition temperature (T-g) of PDXL-PU was lower than that of PEG-PU. Doped lithium perchlorate (LiClO4) salt could be dissolved well in soft segments of PDXL-PU. The ionic conductivity of the PDXL-PU/LiClO4 complex could reach a value of 2 x 10(-5) S/cm at room temperature without the addition of an organic plasticizer. The system with PDXL/PEG as a soft segment had a higher T-g and a lower ionic conductivity than the one with PDXL as a soft segment. (C) 2002 John Wiley & Sons, Inc.