High-surface-area activated carbon obtained from ultra-thin PAN fibers was evaluated as CO2 adsorbent in a simulated flue gas stream. These carbons were prepared from ultra-thin PAN fibers by means of stabilization, activation, and carbonization. By changing the stabilization temperature, it is possible to control the pore size from supermicropores (0.7-2.0 nm) to mesopores (2-5.5 nm). The surface area of the carbon can be over 2500 m(2)g(-1). Both textural properties and nitrogen functionality influence the CO2 adsorption performance of the adsorbents. The ultra-thin PAN fibers stabilized at 533 K (AC533) achieved the highest CO2 gravimetric equilibrium capacity of 5.53 mmol g(-1) in a binary mixture of 15% CO2 in N-2 at 323 K, while AC493 had the highest CO2 dynamic adsorption of 2.70 mmol g(-1) in a N-2/CO2/H2O mixture (83/10/7% v/v) at 323 K. The textural properties, the micropore surface and micropore volume obtained from micropores below 1.1 nm, have a significant effect on CO2 dynamic adsorption. The stabilization temperature affects the nitrogen group present, as determined by XPS, which enhances the specific adsorbent-adsorbate interaction for CO2. (C) 2011 Elsevier B.V. All rights reserved.