In this study, four ammonium-based ionic liquids were synthesized and characterized for carbon dioxide (CO2) removal from natural gas. All ionic liquids (ILs) were synthesized using one-step neutralization reaction. The density, viscosity, 1H-NMR purity analysis and thermal decomposition of the ILs were determined. CO2 absorption of ethanolammonium butyrate EtOHABA, which have the highest decomposition temperature was measured and analyzed at pressure, P ranging from 1 to 29 bar and at three different temperatures, T = 298.15K, 313.15K and 323.15K. The highest CO2 absorption of EtOHABA is at 323.15K, 29 bar which is 0.35 mol fraction. © 2018 Author(s).