The compounds Ba(2)An(S-2)(2)S-2 (An = U, Th) have been synthesized by reactions of the elements with BaS and S at 1273 and 1173 K, respectively. These isostructural compounds crystallize in a new structure type in the tetragonal space group D-4h(15)-P4(2)/nmc. The structure comprises Ba2+ cations and (2)(infinity)[An(S-2)(2)(S)(2)(4-)] layers. The An(4+) cations in these layers are arranged linearly and are bridged by S2- anions. Coordination about the An center, which has symmetry (4) over bar m2, consists of two S-2(2-) ions and four S2- ions. Thus, the compounds are charge-balanced with An(4+). No other alkali-metal actinide chalcogenides are known that contain chalcogen-chalcogen bonds. Optical measurements on Ba2Th(S-2)(2)S-2 indicate a direct band gap of 2.46(5) eV. Density functional theory calculations, performed with the HSE exchange-correlation potential, lead to band gaps of 2.2 and 1.8 eV for Ba2Th(S-2)(2)S-2 and Ba2U(S-2)(2)S-2, respectively, thus demonstrating the utility of applying this functional to 5f-electron systems.