MFI-type zeolitic membranes were prepared by a vapor-phase transport (VPT) method on porous alpha-alumina flat disks. Single- and mixed-gas permeation measurements of butane isomers were performed in the temperature range of 300-375 K. The separation factor was always greater than the ideal selectivity. This result is explained by the preferential adsorption of n-butane on MFI in the binary system. The pervaporation tests for xylene isomers were performed at 303 K. p-Xylene was the most permeable component in the unary system. In the permeation measurements of a binary mixture of p-xylene/m-xylene and a ternary mixture of p-xylene/m-xylene/o-xylene, p-xylene predominantly permeated in the early stage, and then, the Aux of p-xylene decreased gradually and finally became lower than that of the other xylene isomers. The adsorption of m-xylene in the pores of MFI seemed to block the permeation of p-xylene.