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The adsorption and diffusion of pure water, methanol, ethanol, isopropanol, and butanol in microporous silica membranes and (methylated) silica top layer pellets are studied by performing vapor adsorption experiments at 40 °C using a gas chromatograph equipped with a headspace system and using a conventional gravimetrical microbalance, respectively. For silica pellets, the pure vapor adsorption equilibrium is adequately described by a Langmuir isotherm. Adsorption kinetics is described by the internal diffusion model, where surface diffusivities are estimated to be on the order of 10−13 m2/s. The surface diffusivity of water (D S = (5.5−6.2) × 10−13 m2/s) is a factor of 2 higher than the alcohol diffusivities (D S ≈ 3 × 10−13 m2/s). The methylated silica pellets display a higher alcohol adsorption and lower water adsorption. For the microporous silica membranes, methanol adsorption is reduced by a factor of 1000. This may reflect the different structure of the membrane compared to the pellets or the incomplete methanol vapor penetration into the membrane.