A theoretical simulation was performed to study CO2 capture by absorption in a hollow fiber membrane contactor. Three typical alkanolamine solutions of 2-amino-2-methyl-1-propanol (AMP), diethanolamine (DEA) and methyldiethanoamine (MDEA) were employed as absorbents in the analysis. The effects of different sorption systems, operating conditions and membrane characteristics on the removal behavior Of CO2 were investigated. Simulation results indicate that AMP and DEA solutions have much higher CO2 absorption fluxes than MDEA solution, but the concentrations of both AMP and DEA drop dramatically due to depletion. It implies that the separation efficiency and the consumption of absorbents should be taken into consideration simultaneously in terms of absorbent selection in practice applications. The liquid flow velocity, initial liquid concentration and the fiber length as well as fiber radius have significant impacts on the CO2 absorption by AMP and DEA because of their instantaneous reactions with CO2. The reaction kinetics of MDEA with CO2 has been found to be the controlling factor in the process Of CO2 capture in the membrane contactor. Theoretical solution also confirms that the non-wetted mode of operation is favored, by taking the advantage of higher gas diffusivity in order to optimize CO2 capture performance. (C) 2003 Elsevier B.V. All rights reserved.