The solubilities and the physicochemical properties of NaCl-NaAc-H2O (solid liquid system) at 30315 K, 323.15 K, and 348.15 K haVe been measured by the isothermal method. The phase diagrams were plotted according to the measured data. The system only contained the forms of single salts, and no double salts or solid solution. On the basis of the Pitzer model and the temperature coefficients of the single-salt parameters,: the mixed ion-interaction parameters, theta(Cl)-(Ac)- and phi(+)(Na)(Cl)-(Ac)-, as well as the average equilibrium constants of the solids were obtained. Using the above parameters of the solids at equilibrium, the solubility and the activity coefficient predictions for the NaCl NaAc H2O are presented. A comparison between the calculated and experimental results suggests that the solubility data predicted by the Pitzer model agree well with the experimental data.