Vapor pressure of H2O + NaNO3 and H2O + NaNO2 solutions were measured with static method from 298.1 to 353.1 K in a range of salt mass fractions between 0.05 and 0.50. As well, the vapor pressure was determined for quaternary mixtures LiNO3 + NaNO3 + KNO3 + H2O (salt mass ratio 53:5:42) and LiNO3 + KNO3 + NaNO2 + H2O (salt mass ratio 53:35:12) from 313.1 to 353.1 K and total salt mass fraction of 0.30, 0.40 and 0.50. The experimental vapor pressure data of binary systems were correlated with the temperature and the liquid-phase composition using an analytical polynomial equation. The capability of the electrolyte non-random two liquid model (Electrolyte-NRTL) to predict the vapor-liquid equilibrium was evaluated by comparing predicted and experimental data of the mixtures studied in this work. (C) 2010 Elsevier B.V. All rights reserved.