The vacuum vaporization behavior of was studied over the range 1075–1240 K, which is just below the melting point of the material. Both molecular vaporization of and decomposition to K(g), , and contribute to the total vaporization flux. Vapor composition and sublimation thermodynamics were studied by Knudsen cell mass spectrometry, while total vapor pressure and vapor molecular weight were determined by the torsion‐effusion method. Composition data inferred from the mass spectrum, the vapor molecular weight data, and comparison of calculated decomposition pressure with measured total pressure are all in close accord in showing the molecular chromate to account for 83% of the total sublimation pressure. This indicates a high degree of thermodynamic stability for the gaseous chromate. The enthalpy of sublimation of at 1200 K was determined to be from second law slope measurements, from which the standard sublimation enthalpy at 298 K was derived as . An absolute entropy value for derived from the sublimation data is about 12.5 J · K−1 · mol−1 higher than one calculated from fragmentary spectroscopic data, indicating some need for further revision of the molecular constants. Results are compared with those from several other studies and the reasons for similarities and differences are discussed. It appears, that gaseous alkali chromates could play an important role in the hot corrosion of superalloys.