Because composites made of polyester are transformed into three dimensional solid materials during the irreversible cure reaction, a good knowledge of this process is advantageous. The effect of the thermal parameters such as the thermal conductivity and heat capacity of the resin on the process are of great interest. Heat capacity plays an important role because it influences both the heat transferred by conduction and the heat evolved by the cure reaction. Thermal conductivity influences heat conduction alone, and thus is less important. The kinetics of the heat generated by the cure reaction were determined by calorimetry in scanning mode. The study was carried out using a thin sheet of composite heated into the slabs of a mould, with a one-dimensional heat transfer. A numerical model that had been previously tested, provided the precise effect of each parameter on the process.