With the increasing concern about global warming, many technologies have been developed to help mitigate carbon dioxide (CO2) emissions to the atmosphere. The primary motivation for this research has been to investigate the mitigation technology of sequestering the CO2 in deep geological formations, particularly saline aquifers. The displacement of water by CO2    is critically dependent on the physical property known as relative permeability.  By measuring the relative permeability of CO2 gas and water in an experimental apparatus, we were able to determine that the phenomena of CO2 solution and dissolution have very significant effect on the displacement of CO2 gas into water.