Star-shaped macromolecules with six arms of polystyrene grafted onto a fullerene C₆₀ core, or fullerene-containing polystyrene (FPS), were used for the modification of poly(phenylene oxide) (PPO) and the preparation of a dense thin-film membrane. The membrane structure was studied using scanning electron microscopy. The effect of FPS modifier on membrane density and mass transfer of methanol and ethylene glycol through the membrane was studied. Sorption and pervaporation tests were used to determine degree of sorption, diffusion coefficients, flux through the membrane and separation factor. In the pervaporation of a methanol-ethylene glycol mixture over the concentration range of 10-30wt% methanol in the feed, all membranes showed high affinity to methanol. The separation factor reached a maximum at 5wt% FPS in the membrane. The PPO/FPS membranes exhibit the best separation properties when the feed is enriched with ethylene glycol.