Solid-gas phase transition processes of some triazines were studied from kinetic and thermodynamic viewpoint. DSC measurements and Clausius-Clapeyron equation were used to determine enthalpy values related to these processes. Model-fitting methods (based on Arrhenius, Šatava equations and Šesták-Berggren equations) and model-free methods (based on Ozawa-Flynn-Wall and Kissinger equations) allow to hypothesis R2 mechanism. An attempt to determine the activation parameters (ΔH #, ΔG #, ΔS #) related to these processes was carried out. Accordance between the activation enthalpy values with those of activation energy obtained by means of kinetic methods and with the experimental (DSC) and calculated (Clausius-Clapeyron) enthalpy values was found.