An empirical extension of conformal ionic solution theory is presented which describes the solution behavior of a class of reciprocal molten salt systems, the A+qA, B+qB∥C‐qC, D‐qDcharge‐asymmetric systems. The thermodynamic properties of such ternary systems can be calculated from data on the standard free energy change for the metathetical reaction between the 4 pure constituents and solution data on the 4 binary subsystems. Calculated liquidus phase diagrams for the systems Na,Sr∥Cl,NO3; Na,Ba∥Cl,NO3; Li,K∥Cl,CrO4; Li,K∥Br,CrO4; and Na,Ca∥F,Cl agree well with measurements within experimental uncertainties. These systems are illustrative of a wide range of values of the thermodynamic quantities used in the calculations. The equations developed should prove useful as a test of the self‐consistency of reported phase diagrams, as a means of calculating Liquidus temperatures in experimentally inaccessible regions, and as an aid in constructing phase diagrams from a minimum num