In this article a simple mathematical model is presented, which can be used to describe the distribution of reactant concentrations, heat power and temperature in the column of a non-adiabatic flow-calorimeter with a one-point temperature determination, The calculations are based on the properties of a reaction catalyzed by a fixed bed of immobilized enzyme in a so-called enzyme thermistor. With this model it becomes possible to obtain kinetic parameters of enzymatic reactions from calorimetric investigations under conditions of local variation of the reaction rate along the axis of the calorimetric column. It has been demonstrated how the presented model can be used for an optimization of the experimental conditions by means of error simulation. The verification of the model using a real reaction is shown.