A series of poly(ethylene oxide-dimethyl siloxane) copolymers, -[SiMe(2)O(CH2CH2O)(n)](m)-(n = 2, 3, 4, 5, 6.4, 8.7, 13.3), were synthesised by the reaction of polyethylene glycol with dimethyl dimethoxy/diethoxysilane. Corresponding ion-conductive polymers were prepared by complexing these copolymers with salts (sodium tetrafluoroborate or ammonium adipate). The highest conductivity of these systems at room temperature was 3 x 10(-4) S cm(-1) and 6 x 10(-5) S cm(-1), respectively. The glass transition temperature of these copolymers is reported and is seen to be dependent on the length of the ether units. The effects of siloxane content, salt concentration, and temperature on the conductivity are discussed.