Reinvestigation of the Rb+Mo+S system has led to the discovery of a novel family of reduced molybdenum sul5des with the general formula Rb 2n (Mo 9 S 11 )(Mo 6n S 6n؉2 ) (n ؍ 1 to 4) in addition to the previously known compound Rb 2 Mo 6 S 6 . The new rubidium-reduced molybdenum sul5des have been prepared by solid-state reaction of Rb 2 MoS 4 , MoS 2 , and Mo heated at temperatures ranging between 1600 K and 2000 K in a sealed Mo crucible. All members of the family crystallize in the R-3c space group with Z ؍ 6 in the hexagonal setting. X-ray di4raction studies on single crystals showed that their crystal structures consist of an equal mixture of Mo 9 S 11 and Mo 6n S 6n؉2 (n ؍ 1 to 4) cluster units interconnected through Mo+S bonds. The Rb ؉ cations occupy large voids between the di4erent cluster units. When n goes from 1 to 4, the a parameter of the hexagonal unit cell decreases from 9.433(1) A > to 9.237(1) A > , whereas the c parameter increases linearly from 56.27(1) A > to 137.28(2) A > . Extended HuK ckel (tight-binding) calculations revealed that the clusters are hypoelectronic and the Fermi level crosses a rather 6at band for all members of the family. Resistivity measurements carried out on single crystals from 290 K to 2 K con5rmed the metallic behavior and each member was found to be a superconductor with transition temperatures ranging from 4.2 K to 10.9 K.