This study was aimed to determine the sites of protonation of the molecule during the hydrochlorination of 3-amino-2H-1,2,4-triazole. The catalytic reaction was carried out on the site MoS3H2 + and on the site ZnCl2. On both catalysts, the reaction led to a selective protonation of the molecule on the same atom of nitrogen of the cycle. But the reaction is endothermic and exothermic on the MoS3H3 + and ZnCl2 catalytic sites, respectively. The calculation method used is Hartree-Fock (HF) in the lanl2dz basis set.