Lithium p-[methoxy oligo(ethyleneoxy)] benzenesulfonates (LiEOnBS) with different repeating units of ethylene oxide were synthesized, and gel-polymer electrolytes were fabricated using them. The ionic conductivity and lithium ion transport number were measured as a function of salt concentration and repeating unit of ethylene oxide of the LiEOnBS. Temperature dependence of ionic conductivity was well fitted to the Vogel–Tamman–Fulcher (VTF) equation. Lithium ion transport number ( t L i + ) was measured to be in the range of 0.6–0.91 for the gel-polymer electrolytes containing LiEOnBS. The maximum t L i + was obtained to be 0.91 for the 0.1M LiEO3BS in polymer electrolyte. The synthesized LiEOnBS showed single ion transport like characteristics when n was larger than 3.