The capture and storage of carbon dioxide has been identified as one potential solution to greenhouse gas driven climate change. Efficient separation technologies are required for removal of carbon dioxide from flue gas streams to allow this solution to be widely implemented. A developing technology is membrane gas separation, which is more compact, energy efficient and possibly more economical than mature technologies, such as solvent absorption. This review examines the recent patented developments in polymeric based membranes designed for carbon dioxide separation from mixed-gas systems. Initially, the background to polymeric membrane separation is provided, with an overview of past polymeric designs. This is followed by a discussion on the current state of the art; in particular developments in mixed matrix polymeric membranes and facilitated transport polymeric membranes for improved carbon dioxide permeation and selectivity. Recent developments in other membrane types, carbon and inorganic, are reviewed for comparison purposes with polymeric developments. Finally, a brief comment on the future directions of polymeric membrane gas separation technologies is provided.