Significance Ionic liquid/polyvinylidene fluoride composite membrane was successfully prepared by impregnation method and used for the separation on organic chemical hydride process. The separation factors of C6H6/H-2 and C6H12/H-2 in the ternary mixture system were 7500 and 300, respectively. The ionic liquid membrane showed an excellent possibility as a technology of H-2 purification in the organic chemical hydride process by removing aromatic hydrocarbon and cycloalkane simultaneously from the ternary system. (c) 2015 American Institute of Chemical Engineers AIChE J, 62: 624-628, 2016