A thermal diffusivity curve as a function of wet weight basis moisture content constructed for bright tobacco and reconstituted tobaccos, including both blended leaf and samples made via a paper making process, shows that the thermal diffusivity of these materials becomes an approximately linear function of moisture content as the moisture rises above 10% and extrapolates to the thermal conductivity value of water as the moisture content approaches 100%. The data demonstrate that the thermal diffusivity of tobacco is dominated by water, with the intact tobacco and the reconstituted materials falling on the same line, until the moisture content falls to about 10% where a sharp deviation from linearity occurs. Comparison is made to other physical or mechanical properties of tobacco such as heat capacity, the diffusion coefficient of water and compliance which exhibit similar trends. The thermal diffusivity at moderate moisture contents, less than 30%, was calculated from thermal conductivity, density and heat capacity data. The thermal conductivities of the reconstituted materials and tobacco do not fall on the same line whereas the thermal diffusivities do. The thermal diffusivity at very high moisture content, 82%, was directly determined on a blended leaf slurry.