Experimental data on the kinetics of methane gas hydrate decomposition are reported. The isothermal/isobaric semi-batch stirred-tank reactor, used by Kim et al. (1987), was modified to include an on-line particle size analyzer. The experiments were conducted at temperatures ranging from 274.65 K to 281.15 K and at pressures between 3.1 and 6.1 MPa. The model of Clarke and Bishnoi (1999, 2000) was used to determine the intrinsic rate constant. It was found that the activation energy for methane hydrate decomposition is 81 kJ/mol and the intrinsic rate constant of decomposition is 3.6 x 10(4) mol/m(2) Pa.s.