High carbon dioxide (CO2) content in natural gas may constitute some environmental hazards when release to the atmosphere. A variety of conventional separation methods are presently being used to remove the undesired gas fraction from crude natural gas. One promising approach to capture CO2 from natural gas is by formation of gas hydrate. Gas hydrates can be formed in a system containing water and small molecule gases such as CH4 and CO2 at appropriate pressure and temperature conditions. It is important to gain accurate data of the phase behavior of the gas hydrate forming systems to ensure that the process conditions are set in hydrate forming conditions. In this study, thermodynamics modeling approached is implemented to generate the phase equilibria data since the phase behavior measurements are often expensive, tedious and time consuming processes. The thermodynamic program, CSMGem is successfully used for prediction of equilibrium conditions for single and binary hydrate former systems with AAD is less than 10. The program is being further used to predict gas hydrate equilibrium for natural gas with different concentration of CO2. © 2011 Asian Network for Scientific Information.