A flow type apparatus was designed and constructed to measure the solubilities of salts in water vapor at high temperature and pressure. The apparatus was equipped with an additional pure water line to prevent the clogging by precipitated solid salts at the outlet of an equilibrium cell. The solubilities of sodium chloride and potassium chloride in water vapor were measured at 623-673 K and 9.0-12.0 MPa. In order to verify the soundness of this method and the performance of the apparatus, the experimental results for the solubilities of sodium chloride at 673 K were compared with the literature data. The present data are in good agreement with the literature data. The solubilities of sodium chloride are similar to those of potassium chloride at the same temperatures and pressures. The isobaric solubilities decrease with increasing temperature at the experimental pressure range. The experimental results of solubilities were correlated by a solution model. The molar volumes and the energy parameters of salts were treated as adjustable parameters and were optimized with the present and literature data. The adjusted energy parameters for salts can be related to a linear function of the temperature. The correlated results show good agreement with the experimental data. (c) 2004 Elsevier B.V. All rights reserved.