In calorimeter experiments, we obtain the thermogram y = y( t), temperature variation y( t) as a function of time t, when thermal reaction occurs in the calorimeter reaction cell. For thermokinetic studies, we need to know the calorific power generated in the cell, due to the thermal reaction, as a function of time. By use of the frequency transfer function of the calorimeter, we can calculate numerically the calorific power at any time from numerical analysis of the thermogram without any assumption of analytical form of the transfer function. The method is composed of three steps. (1) Experimental determination of the frequency transfer function G of the calorimeter from numerical analysis of the thermogram which is obtained by applying a constant calorific power in the calorimeter cell. (2) Numerical Laplace transform L[ y] = Y of the thermogram which is recorded when the thermal reaction under investigation occurs in the cell. (3) Numerical determination of the calorific power, evolved by the thermal reaction in the cell, by numerical inverse Laplace transform of Y/G. This method is examined in two ways. First, simulation by numerical calculation on a mathematical model calorimeter is done and the accuracy of the method is assured. Second, experiments and numerical analysis on the heat-flow (conduction) type of calorimeter are performed to test the availability of the method.