Radiation grafted poly(methyl methacrylate)-graft-polyimide membranes were prepared for thiophene/hydrocarbon separation. The effects of various grafting conditions such as reaction time, monomer concentration, diluting solvent and initiator amount on the grafting level were investigated. ATR-IR analyses verified the grafting process. Prepared graft modified membranes showed thiophene permselectivity for thiophene/hydrocarbon mixture on pervaporation. At 3.7 % of grafting rate, flux (1.79kg/(m2·h)) and sulfur enrichment factor (3.81) were obtained with 400μg/g feed sulfur content level.