The thermal hazard assessment of toluene nitration in a batch reactor is implemented systematically using an isothermal reaction calorimeter in conjunction with micro-thermal calorimeters. The value of the heat of reaction is determined using calorimetric data, and the kinetic parameters for the desired reaction are derived from the isothermal self-heat rate vs time profiles. A series of safe operation limits are calculated. Results indicate that the desired reaction has a high potential to trigger a thermal explosion, caused by the decomposition of mononitrotoluene. By following these safe operation limits, suppression or elimination of the hazard potential is possible.