A molecular model within a SAFT context for quantitatively predicting the solubility of xenon and oxygen in n-perfluoroalkanes is presented and discussed here. All species are treated as Lennard-Jones chains formed by tangentially bonded spheres with the same diameter and dispersive energy. Optimized meaningful values of both molecular parameters for the pure perfluoroalkanes are also used to accurately predict vapor-liquid and liquid-liquid equilibria of n-alkane + n-perfluoroalkane mixtures. Because of the high nonideality of the mixtures, the Lorentz-Berthelot cross-interaction parameters need to be adjusted using experimental data and ensuring coherent trends. An accurate description of the solubility of oxygen requires additional information to be included in the model. On the basis of ab initio arguments, we considered cross-association between oxygen and perfluoroalkane molecules, which allows solubilities to be described with a deviation below 5%, when compared to experimental data available in the literature and measured in our laboratory.