Electrical conductance and density have been determined as functions of temperature for the two fused binary molybdate systems, K2Mo04-Mo03 and Li2Mo04-Mo03. Data for the two properties in both systems cover temperatures which range up to at least 100°a bove the melting point for each composition. For the single components, the ranges for specific conductances, in ohms cm.-1, are 1.211 at 931.0°to 1.302 at 997.8°for K2Mo04; 4.017 at 790.6°to 6.761 at 939.0°for Li2Mo04; and 0.685 at 823.8°to 0.719 at 820.9°for Mo03. Ranges for the densities, in g. cm.-8, are 2.479 at 935.0°to 2.450 at 988.3°for K2Mo04; 2.888 at 781.2°to 2.802 at 963.4°for 04; and 3.206 at 828.2°to 3.083 at 918.0°for Mo03. When conductances for the first system, K2Mo04-Mp03, are compared at corresponding temperatures that represent a fixed number of degrees above the melting points, resemblance is observed between the conductance-composition diagram and the phase diagram for this system. In plots of either specific conductances or equivalent conductances, at corresponding temperatures, vs. composition, two conductance minima and a single conductance maximum correspond, respectively, to the eutectic compositions and compound composition in the phase diagram for this system. A conductance-composition plot for the second system, Li2Alo04-Mo03, in terms of the more familiar polytherms is also similar to the phase diagram for this system. Although the phase diagram for this system shows peritectic reaction and no compound formation, the composition for the single minimum or true eutectic in the system is the same as that for the conductance maxima in the polytherms. The two kinds of isotherms together with references to the observations of others suggest strongly that correlations may exist between conductance-composition diagrams and the phase diagrams for many molten binary systems. An explanation for the variation of conductance with composition in both systems is based on the nature and relative contributions of the constituent ionic species suggested by the phase diagram. Average activation energies, based on specific conductances, for the single substances and Na2Mo04 at corresponding temperatures that are 100°a bove the melting points decrease in the order Li2Mo04 > Xa2Mo04 > K2Mo04 > Mo03 or Mo02+2 • Mo04-2.(1) This research was supported by National Science Foundation Grant No. 9487 to Howard University. It is based in part on the dissertation submitted by Press L. Robinson to the Graduate School. Howard University, in partial fulfillment of the requirements for the degree, Doctor of Philosophy.(2) K. B. Morris, . I. Cook, C. Z. Sykes, and . B. Templeman, J. Am. Chem. Soc., 77, 851 (1955).