Abstract Several amine-functionalized cation ILs were successfully synthesized, characterized and tested for CO2 absorption studies. Non-functionalized ILs were studied for comparison purpose. The primary amine-ILs have shown higher CO2 solubilities both on molar basis (mol of CO2/mol of IL) and on volume basis (g of CO2/L of IL), compared to non-functionalized and tertiary-amine ILs. Besides amine-functionalization of the cation, anion of the IL has strong influence on CO2 solubility due to its contribution by physical absorption. As a result, the [TF2N]-anion amine-ILs have higher CO2 solubility than [BF4]-anion amine-ILs. Among non-amine functionalized ILs, [P(14)666][TF2N] has the highest CO2 solubility.