A new calibration and desmearing method for a differential thermal analyser (DTA) upon heating and cooling is proposed. The method is based on a heat flux model of the DTA. The parameters in this model represent the DTA independent of heating and cooling rate, and can be determined by measuring two calibration materials. One of these should exhibit a specific heat that varies strongly, possibly non-monotonically, with temperature. Here the ferro- to paramagnetic transition (Curie point) of iron has been used. Upon application of the proposed method, the values obtained for the heat capacity of iron around the Curie temperature were found to be independent of heating or cooling rate, and in agreement with literature data.