The heat capacity of a material is the amount of energy it must receive for its temperature to increase, or give up for it to decrease. It has a crucial role in many fields where thermal phenomena are involved. For thermal storage in the form of sensible heat, it is necessary to have materials with a high heat capacity if a low temperature variation of the storage is desired. The efficiency of gas storage/release by adsorption or desorption in porous structures also depends on their heat capacity. Our study focuses on the influence of mass and mechanical compaction in the experimental determination of heat capacity of powders by differential calorimetry for temperatures between -100°C and 10°C. For this, a polytetrafluoroethylene powder was used. The influence of mass was analyzed by pelleting at different diameters and at a pressure around 1.4 GPa.