Membrane gas absorption technology is a promising alternative for carbon dioxide (CO2) removal from post combustion coal-fired flue gases. This study examines an alternative which consists in absorbing CO2 by ammonia aqueous solution in a membrane contactor to improve the capture processes and to intensify the gas-liquid transfer. Absorption measurements through a membrane contactor have been made. The influence of the material nature constituting the membrane and operating parameters on the capture efficiency has been studied. The results have shown that it is possible to capture CO2 from ammonia through a membrane with capture efficiency greater than 90 %. The membrane limits ammonia losses but does not eliminate it.