A common problem in making thin polymer films by solution processing is the undesirable formation of bubbles during the drying process. These bubbles appear well below the boiling point of the solvent. Experience indicates, however, that the degassing of the polymer solutions reduces bubble formation, indicating a relationship with the presence of air. This work is based on a hypothesis that if the solubility of air in the polymer solution increases with solvent concentration, then the solution can become supersaturated with air as the concentration of the solvent is reduced during the drying process. To test this hypothesis the system poly(vinyl acetate)-toluene-nitrogen was chosen. Previously published data on the solubility and diffusion of nitrogen in the polymer-solvent system were used. Different diffusion models based on the friction coefficients and free-volume model were then used to correlate the diffusivity data so that the diffusion behavior of the ternary system can be predicted over a broad range of conditions. Finally, the thermodynamic and diffusivity correlations were incorporated into a multicomponent drying model which included main and cross-diffusion terms to predict saturation behavior in the polymer solution during the drying process. The model without the cross-diffusion terms represents the ideal system in which the diffusion of one component does not affect the diffusion of others. The drying model did not predict supersaturation of nitrogen when cross-diffusion terms were neglected. Supersaturation of nitrogen was predicted, however, when the cross-diffusion terms are included. Therefore, the cross-diffusion terms in the mass transfer model are essential for the development of nitrogen supersaturation. Also different diffusion models based on the friction coefficients led to qualitatively similar predictions for the supersaturation of nitrogen. The simulation's results supported our experimental observations regarding bubble formation. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 417-428, 2009