Novel ion-conductive inorganic/organic composites were prepared from lithium chloroboracite (Li4B7O12Cl) and polyethylene glycol (PEG). Li4B7O12Cl was stable under ambient conditions and was easily prepared by a sol-gel reaction. The maximum ionic conductivity of the composites was observed when the composite was prepared in the ratio of Li4B7O12Cl/PEG=60/40 (weight/weight), and it was 1.6 x 10(-6) S/cm at 30 degreesC and 2.0 x 10(-5) S/cm at 80 degreesC, respectively. Addition of LiN(SO2CF3)(2) to the polymer matrix of the composites increased the ionic conductivity. The Li4B7O12Cl/PEG composites were mechanically tougher than Li4B7O12Cl itself. (C) 2004 Elsevier B.V. All rights reserved.