The usefulness of poly(dimethyl siloxane-co-ethylene oxide) (P(DMS-co-EO)) copolymer as an ion conducting matrix was investigated. The electrochemical properties were studied by electrochemical impedance spectroscopy and cyclic voltammetry. The glass transition temperature (T-g) and degree of crystallization as a function of salt concentration were examined by differential scanning calorimetry. Ionic conductivities as high as 2.6 x 10(-4) S cm(-1) were determined at 25 degreesC for copolymers films with 5 wt.% LiClO4. These same films had an electrochemical stability window of 5 V. The pseudo-activation energy as a function of salt concentration was obtained using the Vogel-Tamman-Fulcher (VTF) equation.