The lithium ionic conductivities of (La0.52Li0.27)(0.95)Sr0.05TiO2.92 with four different lithium isotopic composition (L-6 i/Li-7=95.56:4.44, 50.00:50.00, 7.42:92.58 and 0.06:99.4) were measured by impedance spectroscopy in the temperature range from 300 to 353 K. The ionic conductivity increased with Li-6 content and the results of the ionic conductivity seemed to follow a classical theory. (C) 2003 Elsevier B.V. All rights reserved.