The title compound, [(UO(2))(2)Cl(2)(OH)(2)(H(2)O)(4)], was obtained unintentionally as the product of an attempted reaction between uranium(VI) oxide dihydrate, UO(3)·2H(2)O, and hydrogen bis-(trifluoro-methyl-sulfon-yl)imide (HTf(2)N), in an experiment to obtain crystals of uranyl bis-(trifluoro-methyl-sulfon-yl)imide, UO(2)(Tf(2)N)(2)·xH(2)O. The structure consists of neutral dimers of uranyl (UO(2) (2+)) units, double bridged by OH(-) anions. Each uranyl unit is surrounded by one Cl and four O atoms, which form an irregular penta-gon, in a plane perpendicular to the linear uranyl groups. The coordination geometry around each U atom can be considered to be distorted penta-gonal-bipyramidal. In the crystal structure the uranyl dimers are connected to each other by hydrogen-bonding inter-actions [O⋯Cl = 3.23 (1) Å].