The thermal behaviour, decomposition kinetics and mechanisms of three diaminotriazole-substituted tetrazine compounds have been investigated using simultaneous DSC-TG and TG/MS techniques. It has been found that TBDM-2NB is much more stable than TBDM-NB and TBDM, where the latter decomposes in two steps with different kinetic parameters. The TBDM decomposes with peak temperature of 379.0 degrees C, while it is 355.6 degrees C and 386.5 degrees C for TBDM-NB and TBDM-2NB, respectively. The activation energy of the first step of TBDM is much higher (176.2 kJ mol(-1)) than the second step (102.3 kJ mol(-1)). The decomposition of TBDM-NB follows 2-d diffusion model, while it is a first order reaction model for TBDM and nucleation growth model for TBDM-2NB. The rearrangement of s-tetrazine ring is typical for thermal decomposition of the title compounds, which may undergo a homo-scission to produce N-2 and followed by production of NH3.