Ionic liquids (ILs) are investigated in many studies to capture CO 2 in recent years.However, almost all of these studies carried out the absorption of CO 2 by ILs at relatively low temperatures (lower than 333.15K or even around the room temperature). Besides, the viscosity of ILs increases dramatically after absorbing CO 2 which could reduce the absorption efficiency significantly. Reversible and efficient absorption of CO 2 at high temperatures was investigated by IL of tetraethylenepentamine acetic acid ([TEPA]Ac) and polyethylene glycol 200 (PEG-200) mixtures with low viscosity. The results showed that the absorption capacity of [TEPA]Ac/PEG-200 mixtures achieved to 1.24 mol CO 2 per mole [TEPA]Ac at 353.15 K at ambient pressure (1.01 bar). The mixtures could be easily regenerated by bubbling dried N 2 through them. The addition of PEG-200 in the [TEPA]Ac could increase the efficiency of absorption and desorption significantly. Furthermore, the solubility data of CO 2 in the [TEPA]Ac/PEG-200 mixtures at T = (353.15, 368.15, 383.15, and 398.15) K under different pressures were measured and the solution enthalpy (∆H sol ) and solution entropy (∆S sol ) were calculated. Under all the conditions, the negative value of ∆H sol indicated that the capture process is exothermic. The process of CO 2 capture described that using [TEPA]Ac/PEG-200 mixtures is a promising approach for CO 2 absorption with high reversibility and excellent absorption property at a relatively high temperature.