A complex of the composition [OsThio 6]Br3 • H2O is synthesized by the reaction of H2OsBr6 with thiourea in a 0.5 M HBr solution. The [OsThio 6]Br3 • H2O complex is characterized using electronic absorption and infrared spectroscopy. The structure of the complex is determined by X-ray diffraction analysis. The crystals are orthorhombic with the unit cell parameters a = 20.510(4) Å, b = 11.186(2) Å, c = 11.892(2) Å, space group Pccn, and Z = 4. The thiourea molecules are coordinated to the osmium atom through the sulfur atom. The osmium atom has an octahedral coordination. The Os-S distances fall in the range 2.39-2.40 Å. The outersphere H2O molecules and Br- anions are involved in hydrogen bonds with the NH2 groups of the thiourea molecules. © Nauka/Interperiodica 2007.