NOVELTY - Carbon dioxide permeable membrane (20) comprises body (26) having first side (32) and opposite second side (34); first regions formed from carbonate, which is partially molten at more than 400 degrees C, forming portion of body and first regions extending from first side of body to second side of body; second regions formed from oxygen conductive solid oxide, combining with first regions to form body and second regions extending from first side of body to second side of body; and body configured to allow carbon dioxide to pass from first side to second side.    USE - Carbon dioxide permeable membrane for carbon dioxide capture in power plants, direct steam methane reforming, and in zero-emission coal-based electric power plant or used in combination with solid oxide fuel cell (SOFC). The membrane is in the form of disk, plate, cylinder, cube, tube, film, or sheet.    ADVANTAGE - The membrane allows simple recovery of carbon dioxide in fuel gas streams.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method of separating carbon dioxide from mixture of gaseous molecules comprising providing carbon dioxide permeable membrane formed from second regions including oxygen conductive solid oxide and first regions including molten carbonate; directing flow of mixture of gaseous molecules toward first side of membrane, mixture of gaseous molecules having temperature at 200-1200 degrees C; creating partial pressure difference carbon dioxide from first side of membrane to second side of membrane; driving flux of carbonate ions from first side of membrane to second side of membrane; and driving flux of oxide ions from second side of membrane to first side of the membrane;and    (2) a method of producing a carbon dioxide permeable membrane comprising forming a body from an oxygen conductive solid oxide; creating pores in body to define a porous continuous structure; and filling pores of porous continuous structure with carbonate.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the carbon dioxide permeable membrane.    Carbon dioxide permeable membrane (20)    Carbon dioxide (22)    Mixture (24)    Body (26)    First side (32)    Opposite second side (34)