In this work a model for the wetting and swelling of pores with water within a Nafion membrane is developed. This model is based on minimizing all contributions to the total free energy of the proposed system. We find that equilibrium state depends on entropic mixing forces and energetic surface forces. The wetting of the pore relies on the entropic forces exceeding the energetic forces. Specifically this indicates a critical pore size in which liquid is the favorable state. If the pore fills with liquid it will swell until balanced by the energy of the deforming membrane. Several factors including pressure relative to saturation and the phase which hounds the membrane are shown to dramatically affect the final equilibrium state of the system.