The onset temperatures (TDsc) of 1H-1,2,4-triazole (1Htri), 3-methyl-1Htri (1Htri-CH3), and 3-amino-1Htri (1Htri-NH2) have been determined by sealed cell differential scanning calorimetry (SC-DSC), and molecular orbital calculations (MO) were performed to clarify the thermal decomposition mechanism and stability criteria of the decomposition pathways. The TDsc values of 1Htri, 1Htri-CH3, and 1Htri-NH2 were determined by the change in the energy of the thermal decomposition pathway model of intramolecular proton transfer combined with bond cleavage. The determined TDsc values are 297 degrees C for 1Htri, 114 degrees C for 1Hti-CH3, and 289 degrees C for 1Htri-NH2. These results agree well with the measured TDsc values of 338 degrees C for 1Htri, 172 degrees C for 1Hti-CH3, and 293 degrees C for 1Htri-NH2. The results reveal that our approach using the thermal decomposition pathways of intramolecular proton transfer combined with bond cleavage of 1Htri, 1Htri-CH3, and 1Htri-NH2 could expand and control application of these compounds. (C) 2017 Elsevier Ltd. All rights reserved.