An experiment has been constructed to measure thermal diffusivity of methane hydrate and methane hydrate-sand/sediment mixtures. Thermal diffusivities of porous methane hydrate (40% pore space filled with methane gas) and mixtures of methane hydrate with Platte Valley sand and Blake Ridge sediment have been measured between the temperature range 265 K and 281 K, at pressures between 4.35 and 7.65 MPa. Thermal diffusivities of porous methane hydrate ranged between 3.1 ¿ 10-7 and 3.3 ¿ 10-7 m2/s. Thermal diffusivity of 0.4 porosity methane hydrate was found to have inverse dependence on temperature, whereas the thermal diffusivity of methane hydrate-sediment/sand mixtures has positive temperature dependence. Thermal diffusivity of methane hydrate-sand/sediment mixtures increased with increasing hydrate volume fraction to a maximum between about 30 and 35 vol% in sand and between about 20 and 40 vol% in sediment. After the maxima, the thermal diffusivities decreased with increasing hydrate volume fraction.