The law of corresponding states of molten alkali nitrates and their mixtures was developed. Pair potential parameters of the pure salts were determined such that the observed molar volume and surface tension were correlated in the corresponding states. Equations for the mixing enthalpy, molar volume, surface tension, electrical conductivity, and viscosity were derived from the corresponding states equations. The estimated mixing properties satisfactorily agreed with the observed ones. Estimation of the mixing properties with two characteristics parameters, characteristics molar volume and temperature, was also discussed.