The paper presents a numerical model for analyzing vapor-liquid equilibrium of ternary (three-component) system at high pressures. The gas-phase non-idealities and solubility of gas in liquid are considered in the numerical model. The model is useful for studies involving evaporation of liquid at different pressure and temperature conditions, where the interface liquid and vapor compositions are required. At high ambient pressures, ambient gases dissolve into the liquid. Thus, even a single component liquid fuel evaporating in a high pressure ambient gas, effectively behaves like a two-component liquid system. This study considers a ternary system. The numerical model has been validated against the experimental data available in literature. The validated model is used to study the solubility of ambient gas in a binary liquid mixture at high pressures. The effects of pressure, temperature and liquid phase composition on the solubility of gas in liquid have been studied systematically. © 2019 Polish Academy of Sciences. All rights reserved.