Permeability of phenol from aqueous solution to organic solvent through a microporous membrane made of cross-linked poly (4-vinylpyridine) (polyvinylpyridine membrane) was about 12 times larger than that through a microporous membrane made of polyethylene (polyethylene membrane) having similar thickness, porosity, and mean pore diameter with those of polyvinylpyridine membrane. Adsorptive or acid–base interaction between phenol molecules and polyvinylpyridine membrane was shown to play an important role in this unusally rapid permeation of phenol through the membrane. The amount of phenol contained in polyethylene membrane per unit volume of the pores was about six times larger than the phenol concentration in the feed aqueous solution. However, the amount of phenol contained in polyvinylpridine membrane per unit volume of the pores was 80–260 times larger than the feed phase concentration. The rapid permeation of phenol through poly-vinylpyridine membrane was thus explained in terms of the extensive enrichment of phenol in the membrane due to the adsorptive or acid–base interaction between phenol molecules and the membrane. © 1993 John Wiley & Sons, Inc.