Li3Sb11S18 was synthesized by a solid-state reaction of stoichiometric amounts of Li2S and Sb2S3. The crystal structure was determined from dark-gray single crystals at 123 K. Li3Sb11S18 crystallizes in the triclinic space group with a = 8.871(1) , b = 11.993(1) , c = 15.407(1) , alpha = 80.014(5)A degrees, beta = 73.599(5)A degrees, gamma = 77.443(5)A degrees, V = 1523.9(2) (3), and Z = 2 (data at 123 K). Both metals have a distorted octahedral coordination by sulfur. These octahedra are arranged in two different types of alternating layers. Strands of trans edge sharing octahedra LiS6 and octahedra SbS6 form heterocubane units LiSb3S4, which are condensed to a rock salt type layer one. Layer two consists mainly of SbS6-units also packed in a rock salt motif. Some of the antimony atoms are replaced by lithium in a systematic way. In total, a deficient rock salt type structure results for Li3Sb11S18. [GRAPHICS] .