The effect of silica and water content on the glass transition temperature, T-g, of MPEG2000-silica-LiClO4 ormolytes was assessed by differential scanning calorimetry (DSC). The sol-gel synthesized ormolytes consisted of various amounts of poly(ethylene glycol) monomethylether (M.W. = 2000 g/mol; i.e., MPEG2000) tethered to silica gel through the hydroxyl terminus via a urethane linkage. DSC features corresponding to physisorbed and hydrogen-bonded water, as well as the glass transition of the polyether, were identified. Both silica and LiClO4 raise the T-g and suppress crystallization of the polyether component. Water plasticizes the polyether and stoichiometrically solvates and sequesters Li+, thereby, lowering Tg. (c) 2005 Elsevier B.V All rights reserved.