The addition of a proper amount of the surfactant lithium dodecylsulfate enhances the ionic conductivity of the composites consisting of low molecular weight poly(ethylene glycol), LiCF3SO3 and ultrafine SiO2 by a factor of five or ten. The optimized conductivity is 4.8 X 10(-5) Scm(-1) at 40 degrees C. The enhancement is associated with the oriented adsorption of the surfactant on the surface of the SiO2 particles.