Understanding the kinetics of carbon dioxide (CO 2 ) hydrate formation in pure water, seawater and porous media aids in developing technologies for CO 2 gas storage, carbon capture and sequestration (CCS) and potentially for methane production from methane hydrates. The present work is focused on understanding the kinetics of CO 2 hydrate formation in pure water and seawater at an initial formation pressure of 6MPa (providing a driving force of about 4.0MPa) and a formation temperature of 276.15K with 75% water saturation in three silica sand particle sizes (0.16mm, 0.46mm and 0.92mm). The seawater (3.3wt% salinity) used in the present study is obtained from sea coast of Chennai (India). It is observed that the gas consumption of CO 2 in hydrate is more for smaller silica sand particle and decreases as the size of the sand increases. The total gas consumed at the end of the seawater experiment is found to be less than the gas consumed at the end of the pure water experiment. This is due to the fact that salts in seawater act as a thermodynamic inhibitor resulting in lower gas consumption of CO 2 in hydrate. The average rate of hydrate formation observed is optimum in 0.46mm particles and is observed to be higher as compared to 0.16 and 0.92mm particles over 10h experimental time. This indicates that 0.46mm silica sand provides an optimum environment for efficient hydrate formation. The study can be useful to understand the suitability of potential sandstone reservoir for CO 2 sequestration in the form of hydrate in the presence of saline formation water.