Aqueous choline-glycine ([Cho][Gly]) solution is a potential candidate for CO2 separation owing to its excellent absorption performance and biodegradability. Moreover, the aqueous solution is easy to volatilize at high temperatures. In this work, H2O was partially replaced with polyethylene glycol (PEG200) and the effect of PEG200 on the CO2 separation performance in [Cho][Gly])/H2O was investigated. The viscosity of [Cho][Gly]/H2O/PEG200 and CO2 solubility in the solution were determined experimentally in the temperature range 308.15-338.15 K at pressures <= 6.5 bar. Further, the measured CO2 solubility was fitted with the reaction equilibrium thermodynamic model and the CO2 desorption enthalpy was estimated. The regeneration performance of [Chol[Gly]/H2O/PEG200 was also evaluated. The results revealed that [Choj[Gly]/H2O/PEG200 has a low CO2 desorption enthalpy and high regeneration efficiency. Particularly, [Cho][Gly]/H2O/PEG200 with 30 wt% PEG200 has a high regeneration efficiency of 95%. Owing to its physical-chemical properties and CO2 separation performance, [Chol[Gly]/H2O/PEG200 shows great potential as an absorbent for CO2 separation. (C) 2019 Elsevier B.V. All rights reserved.