A conductance cell assembly is reported of the capillary design with a cell constant sufficiently high to permit precise electrical conductance measurements with the standard type precision conductance bridge circuits. Important features are the use of single crystal grade MgO for construction of the capillaries that determine the resistance for the electrolyte in the conductance cell, and the use of such materials as gold, or gold‐palladium alloy to construct the various other components of the cell that contact the molten salts. The suspension of the MgO crystal capillaries is of a novel design which permits removal of the capillaries from the assembly for inspection or cleaning, and yet holds these firmly and securely in position during measurements. It is shown that recently published values of electrical conductance for molten KCl and KNO3may be used as standards for calibration of such cells at high temperatures.