2,2′,5,5′-tetrachloro-1,1′-azo-1,3,4-triazole (1) was synthesized by reaction of 4-amino-1,2,4-triazole and sodium dichloroisocyanurate (SDCI). Its structure was determined by X-ray single crystal diffraction. It crystallizes in the triclinicspace groupP-1,with a=6.2824(13)A,b=7.7173(15)A,c=10.443(2)A,α =89.16(3)°, β=88.20(3)°, γ=89.10(3)°, V=505.94(18) A³,Z=2,M_r=301.92, D_C =1.982 mg·m ^-3,F(000) =296 and μ (MoKα)=1.152 mm^-1,the final R=0.0498 and wR =0.1139. X-ray analysis reveals that a stronger π interaction of the triazole units with the tetrazene moiety.