Thermally exfoliated graphene nanoplates were found to be a novel high efficiency sorbent for the capture of CO2. The exfoliated graphene nanoplates were expanded successfully from graphite oxide by a low-heat treatment at temperatures ranging from 150 to 400 degrees C under vacuum conditions. The texture was analyzed by N-2 full isotherms and XRD. The CO2 capture characteristics of the graphene nanoplates at 25 degrees C and 30 bar were examined using a pressure-composition-temperature apparatus. The inter-layer spacing of the graphene layers and pore structure on the CO2 capture capacities were studied as a function of the processing conditions. The prepared graphene nanoplates exhibited high capture capacities, up to 248 wt.%, at 25 degrees C and 30 bar. The improved CO2 capture capacity of the graphene nanoplates was attributed to the larger inter-layer spacing and higher interior void volume. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.