Heat of dilution measurements have been performed on the system H2O/H2SO4/HCl in the concentration range of 0.3 mol% to 20 mol% electrolyte and in the temperature range of 20 degrees C to 60 degrees C. The constituent binary systems H2O/H2SO4 and H2O/HCl could be described using the solvation model introduced by Engels [H. Engels, Anwendung des modells der lokalen zusammensetzung auf elektroytlosungen, Dissertation, RWTH Aachen, 1985]. The vapor-liquid-equilibria (VLE) and the thermal properties are described simultaneously by one set of parameters. Applying the solvation model to the ternary system H2O/H2SO4/HCl, the measured heats of dilution as well as VLE-data taken from the literature could be predicted. The heat of dilution data are presented with a mean relative deviation of 3.5%. The boiling temperatures of the three sources of ternary VLE data considered in this paper are predicted with a mean absolute deviation of less than 1.2 K. The corresponding mean absolute deviations of the vapor mole fractions of HCl are within 0.06.