Ionic liquids are a class of nonmolecular ionic solvents with low melting points.These liquids are unique combination of cations and anions and can provide a variety of different selectivities when used as stationary phases in capillary gas chromatography.We have recently begun evaluating the selectivity and thermal stability of a number of different ionic liquid cation and anion combinations.Selectivity was determined and compared using various isothermal and temperature programmed test mixes.Thermal stability was determined by examining column performance during incremental (destructive) and long-term stability testing at various upper temperatures.Particular cation and anion combinations appear to provide the selectivity similar to polar polyethylene glycol and highly polar cyanosilicone phases while possibly providing higher maximum temperature stability.