The electrical conductivities of solid La0.55Li0.35TiO3 electrolytes at different Li intercalation levels were measured, in situ, using a special cell and electrode design. The relative changes in electrical conductivities of La0.55Li0.35TiO3 at different Li insertion levels in liquid electrolytes were monitored by the voltage across the La0.55Li0.35+xTiO3 powder disk electrode sandwiched between two nickel screens and charged only on one nickel screen. The real electrical conductivities of the La0.55Li0.35+xTiO3 ceramic at different Li insertion levels x without influence of high-ion-conductivity liquid electrolytes was measured by electrochemical impedance spectroscopy using sintered La0.55Li0.35+xTiO3 disk electrodes with Au coating on both sides. Lithium was electrochemically inserted into La0.55Li0.35TiO3 when the Au coated disk electrodes were immersed into liquid electrolytes with the cell inverted. The impedances of La0.55Li0.35+xTiO3 electrodes were then measured with the disk electrode suspended above the liquid electrolyte with the cell upright. (C) 2004 The Electrochemical Society.