The purpose of modelling the processes of compression and thermal softening of particulate, as well as porous and anisotropic materials is to determine the critical stress condition which initiates plastic flow of the material. This value is critical for the effectiveness of thermal softening process and depends on the thermo-mechanical parameters of the material and the key parameters of the process itself [2,4]. As it has been proven by research, the strength of materials such as wood and sawdust evidently decreases with the increase of temperature, influenced also by the moisture content of the material. For determining the distribution of temperature in a layer of thermally softened material it is indispensable to determine the heat transfer coefficient. This paper presents a test fixture for measuring heat conduction in natural composites materials, allowing for the effect of temperature, developed by the author.