The UV-vis absorption, thermal analysis, ionic conductivity, mechanical properties, and morphology of a blend of poly(dimethylsiloxane-co-ethylene oxide) [P(DMS-co-EO)] and poly(epichlorohydrin-co-ethylene oxide) [P(EPI-co-EO)] (P(DMS-co-EO)/P(EPI-co-EO) ratio of 15/85 wt %) with different concentrations of LiClO4 were studied. The maximum ionic conductivity (sigma = 1.2 x 10(-4) S cm(-1)) for the blend was obtained in the presence of 6% wt LiClO4. The crystalline phase of the blend disappeared with increasing salt concentration, whereas the glass transition temperature (T-v) progressively increased. UV-vis absorption spectra for the blends with LiClO4 showed a transparent polymer electrolyte in the visible region. The addition of lithium salt decreased the tensile strength and elongation at break and increased Young's modulus of the blends. Scanning electron microscopy showed separation of the phases between P(DMS-co-EO) and P(EPI-co-EO), and the presence of LiClO4 made the blends more susceptible to cracking. (C) 2004 Wiley Periodicals, Inc.