Poly(hexyl methacrylate), which is expected to show affinity toward benzene rather than cyclohexane, was introduced onto nylon 6 by radical graft polymerization of hexyl methacrylate. The membranes from modified nylon 6, having poly(hexyl methacrylate) as a side chain, permeated benzene in preference to cyclohexane from benzene/cyclohexane mixtures by pervaporation. From the pervaporation and the sorption experiments, it was made clear that the introduction of poly(hexyl methacrylate) onto nylon 6 membrane led to the enhancement of permselectivity toward benzene. The solubility data for benzene were described by a combination of simple and specific sorptions, while those for cyclohexane were described by simple sorption.