The presence of porous media such as activated carbon has been known to enhance the hydrate formation rate and the amount of gas consumption for methane storage applications. However, information on the effects of porous media particle size on the formation and dissociation kinetics is very limited or not available. Activated carbons with different particle sizes, 250-420 mu m, 420-841 mu m, and 841-1680 mu m, were used in order to investigate their effects on the methane hydrate formation and dissociation. The methane hydrate formation experiments were conducted at 8 MPa and 4 degrees C in a quiescent fixed bed crystallizer. The result showed that the experiment conducted with the 8411680 mu m activated carbon showed the highest average water conversion to hydrate, 96.5%, due to its large interstitial pore space between the activated carbon particles, which were observed by the two-step methane consumption. In contrast, the highest average percentage of methane recovery, 98.1%, was achieved in the methane hydrate dissociation experiment conducted with the 250-420 mu m activated carbon. (C) 2014 Elsevier Ltd. All rights reserved.