The vapor pressure of ammonia + lithium nitrate + water and ammonia + lithium nitrate mixtures was measured by a static method from (293.15 to 353.15) K in ammonia mass fractions ranging from 0.2 to 0.6. The experimental vapor pressure data were correlated with the temperature and the liquid-phase composition using an analytical polynomial equation. The capability of the electrolyte nonrandom two liquid (E-NRTL) model to predict the vapor−liquid equilibrium (VLE) of the ternary mixture was evaluated by comparing predicted and experimental data of the ammonia + lithium nitrate + water solutions. The binary interaction parameters of ammonia + lithium nitrate needed for the prediction of ternary VLE were determined from binary experimental data.