Ionic liquids are capable of acting as solvents for amine CO2 absorbent compounds in CO2 separation processes and when so used enhance the sorption of the CO2 by the amine. A cyclic sorption process for separating CO2 from a gas stream, such as flue gas or natural gas, brings the gas stream into contact with an absorbent solution of an amine CO2 sorbent in an ionic liquid solvent followed by desorbing the CO2 to regenerate the amine.