The development of novel materials for carbon dioxide (CO2) capture is of great importance in resource utilization and environmental preservation. In this study, imidazolium-based ionic liquids (ILs) with symmetrical ester and hydroxyl groups were prepared, and their corresponding polymer were synthesized by melt condensation polymerization. The structure and properties of the poly(ionic liquid)s (PILs) were characterized by proton nuclear magnetic resonance, gel permeation chromatograph, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. In addition, the CO2 sorption behavior of the IL monomers and PILs were studied at a low pressure (648.4 mmHg CO2) and under a temperature of 25°C using a thermogravimetric analyzer. The CO2 sorption capacity of 1,3-bis(2-hydroxyl ethyl)-imidazolium hexafluorophosphate ([HHIm]PF6, 10 mol%) was the highest among all the IL monomers and PILs studied. This capacity is also much higher than those reflected of previously reported ILs. Moreover, the sorption equilibrium of [HHIm]PF6 was achieved within a short time. Copyright © 2011 John Wiley & Sons, Ltd.