A simple model for predicting gas solubilities of O-2 and CO2 at low pressure and near ambient temperature in solutions of salts, sugars, and organic solvents (alcohols, ketones, ethers, aldehydes, etc.) is proposed. It is derived from the Van Laar assumptions and takes account of size differences between molecules in solution by their volumetric fraction. It is a group contribution model where anions and cations are considered as groups and other molecules are treated as in the UNIFAC (UNIQUAC Functional group Activity Coefficients) procedure. Pseudo-Henry＇s constants for groups were determined using solubility data in aqueous solutions containing only one salt, one sugar, or one organic compound at 25 degrees C. The predictive performance of the model was evaluated by comparison with experimental data using multicomponent aqueous salt-sugar mixtures. The model was used to estimate solubilities of oxygen and carbon dioxide in fermentation media.