Calorimetry is one of the oldest areas of physical chemistry. The date on which calorimetry came into being may be taken as 13 June 1783, the day on which Lavoisier and Laplace presented a contribution entitled ,,Memoire de la Chaleur“ at a session of the Academie Française. Throughout the existence of calorimetry, many new methods have been developed and the measuring techniques have been improved. At p- sent, numerous laboratories worldwide continue to focus attention on the development and applications of calorimetry, and a number of com- nies specialize in the production of calorimeters. The calorimeter is an instrument that allows heat effects in it to be determined by directly measurement of temperature. Accordingly, to determine a heat effect, it is necessary to establish the relationship - tween the heat effect generated and the quantity measured in the ca- rimeter. It is this relationship that unambiguously determines the mathematical model of the calorimeter. Depending on the type of ca- rimeter applied, the accuracy required, and the conditions of heat and mass transfer that prevail in the device, the relationship between the measured and generated quantities can assume different mathematical forms.