For the determination of the heat of a given process with a differential scanning calorimeter, it is not only necessary to measure the DSC curve, but also to construct the baseline. If the differential scanning calorimeter is coupled with a balance, the gravimetric measuring values can be used for the construction of the baseline. In this paper, the model of an input function was calculated from a model equation of the baseline and the gravimetric signal. The corresponding output function results from this together with a model apparatus function by calculation of the convolution integral. Using the regression analysis, the required model coefficients were obtained from the experimental DSC values. To prove the given model, it was applied to investigations of the desorption process of adsorbed water on zeolites by simultaneous TG-DSC measurements. It was found that with the help of this model, by integration of the corresponding DSC curves, suitable enthalpy values could be obtained even for unfavourable shapes of the baseline.