Fe2Mo powders have been produced from Fe2MoO4 powders by gas - solid reduction using pure H-2 gas at 1023 and 1173 K. The thermal diffusivity of the cold-pressed Fe2Mo powders having a relative density between 0.52 and 0.72 has been measured at room temperature both in air and in vacuum using the laser-flash method. A correlation was observed between the thermal diffusivity and the relative density for the powders reduced at different temperatures, regardless of the difference in microstructure of the powders. In order to explain the porosity dependence of the effective thermal conductivity, a new simple method developed based on the Ohm's law models was used. The model successfully simulates the experimental data, and the thermal conductivity of bulk Fe2Mo was estimated as 10.8 W/mK.