In these potentiometric sensors, a mixed binary carbonate sensing material consisting of 90 mol% Li2CO3 and 10 mol% BaCO3 was modified by adding ceramic oxide materials such as SiO2, B2O3, La2O3, Bi2O3, CeO2 and In2O3 in different mol% concentrations. Various sensors mixed with these external oxides have shown good performance at operating temperatures below 300 degrees C. Scanning electron microscopy reveals that a glassy sensing phase is formed-in the sensing bi-carbonate by the addition of ceramic oxides and sintered at 600 degrees C for I h. The sensor mixed with SiO2:B2O3:Bi2O3 in 1:2:1 mol% showed an excellent response and recovery characteristics and followed a fair Nernstian behavior with a Delta EMF/dec value of -48.18 at as low as 150 degrees C. The decrease in operating temperature is attributed to the enhanced lithium ion migration through the glassy sensing phase of the sensing electrode. (C) 2007 Elsevier B.V. All rights reserved.