The electrical conductivities of aluminum chloride‐potassium chloride mixtures were measured over the composition range 15–80 m/o (mole per cent) and at temperatures of 180°–1080°C. A minimum at 33 m/o and a maximum at 50 m/o were observed in the equivalent conductivity as a function of composition. The system was considered as consisting of the two binary systems, and , since the compound is extremely stable in the liquid. The compound had a maximum specific conductance with temperature near 1000° C. The negative deviations of conductivity isotherms for the system are apparently due to large differences in anion polarizabilities, whereas the positive deviations for the system are attributed to basic changes in melt structure.