In the present work, the heat transfer behavior of CO2 hydrate dissociation was studied in three quartz sand particles (QS-1, QS-2 and QS-3) with varying grain sizes. The heat transfer behavior was evaluated by determining the heating rates of the porous media (quartz sand) during the CO2 hydrate dissociation process in 3.3 wt. NaCl. The experiment was performed using sandstone hydrate reactor by first forming the CO2 hydrates at 4 MPa and 274.15 K and then dissociating the hydrates from 274.15 to 277.15 K, respectively. The results indicate that the thermal response of the porous sediment was significantly influenced by the hydrates as well as the porous sediment properties. The heating rate of the porous media increased when the grain size increased. However, the presence of CO2 hydrates reduced the heat transfer behavior of the porous sediment due to the endothermic nature of hydrate dissociation. The heating behavior of the porous media with hydrates mainly depends on the type and pattern of hydrate formed (pore-filling, loadbearing, and cementation) and the location of the hydrates within the pores of the porous sediment. The pore-filling type of hydrate formation in porous sediments provides high thermal stability for CO2 hydrate storage due to its less contact with the quartz sand particles. However, the pore-filling hydrate formation type is challenged with low or undesired CO2 hydrate storage capacity. These findings will provide meaningful insights to select favorable sediment properties/sites for CO2 storage in the hydrate form in porous sediments. © 2023, Association of American Publishers. All rights reserved.