The new uranyl sulfide anion [(UO2)S4](6-) has been synthesized and characterized as a cation-stabilized anion in the compound Na2Ba2(UO2)S4. This compound was synthesized at 873 K from the solid-state reaction of uranium, Na2O2, BaS, and sulfur. The coordination about the U(6+) center in [(UO2)S4](6-) is square bipyramidal with the uranyl O atoms 180° apart and four equatorial S atoms. The Na(+) and Ba(2+) cations form interactions with the uranyl O atoms. Despite the inherent difficulties involved in the synthesis of complex uranium oxysulfides, it is demonstrated that under the right reaction conditions the UO2(2+) species can be produced in situ and result in totally new chalcogen derivatives.