The ion-conduction properties of a polyethylene oxide (PEO)-based composite polymer electrolyte comprised of PEO, LiClO{sub 4}, and the ferroelectric material BaTiO{sub 3} were studied. The addition of BaTiO{sub 3} resulted in an increase in conductivity over the temperature range 25--115 C. The optimum amount of BaTiO{sub 3} (purity 99.9%, particle size 0.6--1.2 {micro}m) was 1.4 wt %, which is very low in comparison with previously reported composite polymer electrolytes. The ionic conductivity of a composite polymer electrolyte containing 1.4 wt % BaTiO{sub 3} was 1 {times} 10{sup {minus}5} S/cm at 25 C, which is at least one order of magnitude higher than that of the pristine polymer electrolyte (4 {times} 10{sup {minus}7} S/cm). The transport number of the lithium ion in this composite polymer electrolyte was higher than that of the pristine polymer electrolyte. The increase in the conductivity and the lithium-ion transport number is explained on the basis of the spontaneous polarization of the ferroelectric material due to its particular crystal structure. The addition of BaTiO{sub 3} powder greatly enhanced the lithium/electrolyte interface stability.