NOVELTY - Gas absorption membrane comprises: a substrate having micropores that extend through the substrate to allow a gas phase to penetrate into the substrate; and a thin hydrophobic coating on one side of the substrate in which the pores of the substrate are substantially unobstructed by the coating so that the gas phase can penetrate the pores, and the coating opposes or substantially resists a liquid solvent for absorbing carbon dioxide, from penetrating the pores of membrane from the side having the coating so that carbon dioxide in the pores of substrate is transferred to the liquid solvent.    USE - The gas absorption membrane is useful for: separating carbon dioxide from a gas phase including a flue gas of a coal fired power station; the mass transfer of a targeted substance (all claimed); and processing streams of cement, iron and other metal refining plants.    ADVANTAGE - The gas absorption membrane has usable life of up to 2 or 3 years.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a gas absorption membrane for separating carbon dioxide from a gas phase, comprising: a hollow fiber substrate having micropores that extend from an internal lumen of the substrate to an outer face of the substrate; and a thin hydrophobic coating on inner and/or outer surfaces of the substrate, where the pores of the substrate are substantially unobstructed by the coating and when in use, a liquid solvent is conveyed in the lumen of the membrane and the gas phase on the outside of the membrane;    (2) manufacturing the gas absorption membrane for separating carbon dioxide from other gas species, comprising: locating a thin film substrate having micropores that extend through the substrate in a physical vapor deposition chamber; locating a targeted material in the chamber; and generating a plasma in the chamber so as to deposit or sputter a thin coating of the targeted material onto at least one side of the substrate without substantially obstructing the pores of the substrate; and    (3) manufacturing a membrane that facilitates the mass transfer of a targeted substance, comprising: locating a thin film substrate having micropores that extend through the substrate in a physical vapor deposition chamber; locating a material on an electrode on the chamber to be sputtered onto the substrate; and generating a plasma in the chamber so as to deposit or sputter a thin coating of the material onto at least one side of the substrate without substantially obstructing the pores of the substrate, where the coating is hydrophobic.