Developing novel hybrid absorbents is essential for CO 2  separation. In this study, the density and viscosity of a hybrid absorbent (choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water (ChoPro/PEG200/H 2 O)) were measured experimentally, and its CO 2  solubility was also determined. The excess mole volume and excess Gibbs energy of activation of the hybrid absorbent were further estimated to understand the molecular structure and interactions between ChoPro/PEG200 and H 2 O. The CO 2  solubilities in ChoPro/PEG200 and ChoPro/H 2 O were analyzed and described using the Redlich–Kwong non-random-two-liquid (RK-NRTL) model. Furthermore, the CO 2  solubility in the hybrid absorbent was predicted using the RK-NRTL model and was compared with the new experimental results for verification. The effect of H 2 O on the CO 2  absorption performance was further analyzed. The performance and cost of the hybrid absorbent were compared with those of other commercialized CO 2  absorbents. In addition, the recyclability of the hybrid absorbent for CO 2  separation was studied. The results of this study indicated that the hybrid absorbent could be promising for CO 2  separation.