The title crystal structure, Cs[ReCl(4)O(2)], consists of cis-tetrachloridodioxidorhenate(VII) anions and caesium cations. The distorted octahedral anion has nearly C(2v) symmetry, with a cis arrangement of the oxide ligands. The Re-Cl bond lengths for the Cl atoms trans to the oxide ligands are affected by the trans influence of the Re-O bonds and are longer than for the Cl atoms cis to the oxide ligands [average of 2.472 (2) A versus average of 2.322 (2) A, respectively]. There are ten Cl atoms from six cis-tetrachloridodioxidorhenate(VII) anions in the neighbourhood of the caesium cation.