The signal produced by a pseudo-adiabatic calorimeter is simulated by numerical solution of the differential equations that model the chemical kinetics [1], the thermal properties of the calorimetric cell [2], and the response of the thermistor used as a thermometric sensor [3]. These equations show that the calorimetric signal is related with concentration in a complex way. Therefore, a comparison between the signals of the three basic kinetics reactions (zero, first and second order) was made, as a first step to obtain a standard procedure to follow chemical kinetics using a calorimeter. In order to help understanding this relationship, the initial rate method was applied to the simulated data to assess the relationship between the order and the kinetic constants calculated with those used for the simulations. As it was expected, the initial rate method for the calorimetric data, do not give a slope directly related with the order of the reaction, as it would be produced, for example, in data from a spectrophotometer. However, a linear relationship was found between what we call the “calorimetric order” and the kinetic order. Finally, the developed procedure was applied to the study of the H2O2 decomposition catalyzed with Fe3+ in homogeneous phase and with activated carbon in heterogeneous phase, finding the order and the kinetics constants of the global processes, which were in close agreement with those in the literature.