Poly(ethylene oxide) (PEG) oligomers having charged groups on the chain ends, PEO/salt hybrids, were prepared as ion conductive matrices. Since the anion sites were fixed to the PEO chain ends, these were expected to be a single-ion conductors. The effect of terminal structure on the ionic conductivity of the potassium ions with PEO molecular weight of 1000 was analyzed. Most of these PEO/salt hybrids showed amorphous phase in a wide temperature range and were confirmed to have low glass transition temperature from -55 to -30 degrees C. They showed high ionic conductivity attributed to a relatively high cation mobility at ambient temperature. PEO oligomers having methyl sulfonamide potassium salt on both ends of PEO showed the best ionic conductivity of 8.5 X 10(-6) S/cm at 25 degrees C when the molecular weight of PEO part was 1000. It was suggested that the ionic conductivity of the PEO/salt hybrids was mainly governed by the dissociation energy of the introduced terminal groups.