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Sorption of ethanol and water in bi-dispersed pellets formed by compaction of a hydrophobic crystalline molecular sieve, silicalite, is examined. The difficulties inherent in the measurement and interpretation of mixed liquid adsorption equilibria are discussed and the individual adsorption isotherms for {ethanol-water}/silicalite crystals presented. The adsorbed ethanol exhibits a density similar but smaller than that of liquid ethanol. The adsorbed water, however, is as much as four times lighter than liquid water. Diffusion of ethanol in the silicalite micropores is reasonably well described with a constant diffusivity of 5 × 10⁻¹⁴m ²s⁻¹. The intracrystalline diffusivity of water is higher than that of ethanol at low loading but is drastically reduced as saturation is approached. A sensitivity analysis based on a detailed theoretical model yields the characteristic time constants of 3.3 s for external boundary layer mass transfer, 83 …