Abstract: 5-[(3,5-di-Bromo-2-Pyridyl) Azo]-2,4-diaminotoluene(3,5-di-Br-PADAT) is a highly sensitive and selective reagent for cobalt and copper. The single crystal belongs to space group P2₁/n with lattice parameters. a = 11.477(5)Å, b= 15.642(6)Å,c = 8.311(4)Å,α= 110.54(4)° and 4 molecules in the unit cell. The intensities of 1960 independent reflections were collected using the PW-1100 four-circle diffractometer, The structure was solved with patterson method and heavy-atom method and refined to a final R= 0.0611 by full matrix least square method.