One of the new approaches for capturing carbon dioxide from treated flue gases (post-combustion capture) is based on gas hydrate crystallization. The basis for the separation or capture of the CO2 is the fact that the carbon dioxide content of gas hydrate crystals is different than that of the flue gas. When a gas mixture Of CO2 and H-2 forms gas hydrates the CO2 prefers to partition in the hydrate phase. This provides the basis for the separation of CO2 (pre-combustion capture) from a fuel gas (CO2/H-2) mixture. The present study illustrates the concept and provides basic thermodynamic and kinetic data for conceptual process design. In addition, hybrid conceptual processes for pre and post-combustion capture based on hydrate formation coupled with membrane separation are presented. (C) 2007 Elsevier B.V. All rights reserved.