The use of ionic liq.-polymer in supported ultrafiltration membrane in vacuum pervaporation has been verified. The ultrafiltration membranes were impregnated by two ionic liqs. (1-ethenyl-3-ethyl-imidazolium hexafluorophosphate and tetrapropylammonium tetracyano-borate) and polydimethylsiloxane. These new and very stable supported ionic liq.-polymer membranes were used for sepn. of ternary mixts. butan-1-ol-acetone-water by vacuum pervaporation. In comparison with polydimethylsiloxane membranes, the av. enrichment factor of butan-1-ol increased in both cases. This higher selectivity shows a good potential for improving pervaporation sepn. process.