In order to assess the high temperature vaporization behavior and equilibrium gas phase compositions of binary alkali metal oxides, the relevant thermodynamic and molecular constant data have been compiled and critically evaluated. Selected values of the Gibbs energy and enthalpy functions of condensed and vapor phases are given in the form of equations valid over wide temperature ranges, along with the standard entropies and enthalpies of formation. These data were used to generate plots of the equilibrium partial pressures of vapor species as functions of temperature for representative conditions ranging from reducing to oxidizing. Maximum vaporization rates have been calculated using the Hertz–Knudsen equation. Literature references are given.