Poly(ethyleneimine) (PEI) impregnated adsorbents are promising alternatives to amine-based liquid absorbents for post-combustion capture of CO2. A current challenge is to identify meso- and/or macroporous supports with large pore volumes that can be facilely synthesized from a cost-effective approach as supports for PEI. In this work, hierarchically nanoporous poly(divinylbenzene) (PDVB) is synthesized through a one-step polymerization of readily available divinylbenzene (DVB) under solvothermal conditions without use of any template or catalyst. The synthesized PDVB is found to have abundant mesomacropores, as well as a large pore volume. Subsequently, a series of PEI-impregnated PDVB sorbents is prepared and their performance for the selective adsorption of CO2 is investigated. The PEI-PDVB composites are found to exhibit promising CO2 capacities and exceptionally high CO2/N-2 selectivities. The strength of CO2 adsorption is experimentally determined by direct calorimetric measurements. The PEI-PDVB composites show excellent stability under both dry and humidified sorption conditions during extended adsorption-desorption cycles. Based on the results obtained, these PEI-PDVB composites are identified as sorbents with significant potential for application in practical CO2 capture from industrial gas streams. (C) 2016 Elsevier B.V. All rights reserved.