The selective removal of acid gases from a contaminated gas stream was studied using a new type of amines that have more than one amino-group in a facilitated transport membrane. Four different amines, i.e., 1,2-diaminoethane (diamine), diethylenetriamine (polyamine), di(2-ethylhexyl)amine, and diethylamine, were tested and the transport rate through a facilitated transport membrane and selectivity of CO 2/CH 4 gas mixture of the tested amines were compared. The CO 2 permeance decreased with increasing CO 2 feed pressure, whereas the permeance of CH 4 remained mainly constant for all amines tested. The permeance of both CO 2 and CH 4 was almost constant with CO 2 feed pressure for the two amines used resulting in a constant selectivity for both di(2-ethylhexyl)amine and diethylamine. Diethylenetriamine showed the highest CO 2 permeance and the lowest CH 4 permeance. High permeance of CO 2 and high selectivity of CO 2/CH 4 mixture using these amines were attributed to higher number of amino-groups which possibility increased the loading the capacity, as compared with other amines tested. The effect of amine concentration on both permeance and selectivity using diethylenetriamine as the liquid membrane showed that the both permeance and selectivity of CO 2 increased with increasing amine concentration ≤ 1 M. Amine concentrations of > 1 M showed no additional effect on CO 2 permeance. This is an abstract of a paper presented at the 7th World Congress of Chemical Engineering (Glasgow, Scotland 7/10-14/2005).