The structure of the cis-dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) have been studied by means of single-crystal X-ray diffraction. The data are described in orthorhombic unit cell with space group Pccn (No. 56) at 295 K, a = 28.478(4) ?, b = 10.900(6) ?, c = 11.697(13) ?, and V = 3631(4) ?3, Z = 8. The crystal structure of the title compound comprises a nearly octahedral configuration with a Ru-O bond distance of, 2.151 ?, and the average values of, 2.269 ? and 2.421 ? for Ru-S and Ru-Cl, respectively.