The apparent densities, coefficients of thermal expansion (CTE), and softening points of the BaO-Al2O3-SiO2-B2O3 glasses prepared in this study range from 2.61 to 3.92 g/cm(3), 4.92 to 10.98 ppm/degrees C, and 656 to 854 degrees C, respectively, depending on the glass composition. The softening point decreases with increasing BaO or B2O3 content in the glass. The feasibility of using Mgo, KAlSi2O6, and KAlSiO4 to tune the CTE of BaO-Al2O3-SiO2-B2O3 glass is investigated. Composites containing MgO additive show little change in CTE at high temperature and report a high structural stability with the change in time. Wetting angle of the glass on the YSZ substrate depends to a great extent on the soaking temperature and the BaO content in the glass. Composites of selected BaO-Al2O3-SiO2-B2O3 glasses and MgO additive on the YSZ substrate are evaluated for use as sealing material of solid oxide fuel cells (SOFCs). Results indicate that leakage rates for the composites of L06-20 vol% MgO, L08-30 vol% MgO, and L09-40 vol% MgO are lower than the detectable limit in this study. (c) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved