The influence of the temperature program parameters of an ODSC experiment on the calculated “reversing” and “kinetic” signals has been studied. Mixed orthophosphate salts of KMPO₄ (where M=Ni²⁺, Co²⁺ and Fe²⁺) which present at least one structural phase transition have been used for this purpose. On these crystalline compounds we have shown that the non reversing heat flow is partly associated with the formation and disappearance of ferroelastic and ferroelectric domain walls. However a proper choice of the temperature program parameters is important so that the calculated “reversing” and “kinetic” curves have the supposed physical meaning according to the assumptions made for the calculations.