The specific conductances of LiClO4, LiPF6 and LiAsF6 in concentrated solutions of propylene carbonate (PC)–diethyl carbonate (DEC) mixtures at 15, 20, 25, 30, 35 and 40°C were measured and the data were treated with an empirical equation. Specific conductances, against concentration, temperature, and solvent composition plots are given, as well as concentration that corresponds to the maximum specific conductance, against concentration. Activation energies were also calculated from temperature dependence of specific conductance. The three salts mentioned above, as well as LiBF4, were tested as electrolyte solutions with PC–DEC, in Li/Li1.05Mn2O4 cells.