The reaction of NiCl2 and 3‐hydrazine‐4‐amino‐1,2,4‐triazole (Hatr) in the mixed solvent of EtOH and H2O yielded a dimer compound ([Ni2(Hatr)2(H2O)2(EtOH)2Cl2]Cl2·EtOH) with water and EtOH molecules coordinated to nickle ions. It crystallized in trigonal space group R‐3, a=b=29.67(1) Å, c=8.95(7) Å, β=120(1)°, as determined by single‐crystal X‐ray diffraction. Then, they were fully characterized by the IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and elemental analysis.