Room temperature ionic liquids (RTILs) are salts with melting point close or below room temperature. Changing the nature of the anion or the cation produces a new salt that may or may not be a RTIL. The physico chemical properties of RTILs are briefly reviewed. The partitioning of 38 aromatic derivatives with acid, base, or neutral functionalities was studied between the biphasic liquid system 1‐butyl‐3‐methyl imidazolium hexafluorophosphate (BMIM PF6) and water. It was found that the viscosity of pure RTILs is too high for direct use as a liquid phase in countercurrent chromatography (CCC). The addition of a third solvent was needed to decrease viscosity. The ternary phase diagrams of BMIM PF6–water and acetonitrile, methanol, ethanol, 1‐propanol, and 2‐propanol are presented in mass and mole percentages. The organic solvent‐RTIL–water systems form two liquid phases with a viscosity low enough to allow CCC operation which was not done, due to the low amount of RTIL prepared.