The main goal of this research work is to propose a convenient model that describes the evolution of the latent heat during a full transformation cycle and defines the thermal-induced phase transformation behavior of the NiTi shape memory alloy under zero stress conditions. The proposed model is constructed based on experimental data obtained from Differential Scanning Calorimetry (DSC) analyzes, carried out at various cooling/heating rates. The NiTi thermal behavior was studied and modeled across the different temperature ranges of the thermal transformation cycle. The developed constitutive equations were implemented in the Matlab software. The expression of the enthalpy change during both forward and reverse phase transformations was predicted as function of the cooling/heating rate. Moreover, the transformations temperatures were theoretically determined from the proposed model and compared to the experimental ones. A good agreement between experimental and theoretical findings proves that the proposed model provides a precise estimation. The efficiency of the adopted hypotheses is well confirmed.