In the present invention, there is disclosed a gas separation apparatus from a mixture of gases by passing thereof through a membrane wall of a liquid film formed by a separation solution that supports the formation of the liquid film, wherein the invented gas separation device comprises a system of rods (4) separated from each other and from which at least portion is adapted for contact with the separation solution source and which rods (4) are arranged in a developed surface (21, 22) at a mutual distance enabling the formation of the liquid film, whereby a gas mixture inlet (1) and a concentrated gas mixture outlet (7) are connected to one side of the developed surface (21, 22), while a separated gas withdrawal outlet is connected to the other side thereof. The developed surface (21, 22) can have the form of a flat surface (21) or a cylindrical surface (22).