BiS crystallizes in the orthorhombic Fmm2 space group. The structure is one-dimensional and consists of four BiS ribbons oriented in the (1, 0, 0) direction. there are three inequivalent Bi2+ sites. In the first Bi2+ site, Bi2+ is bonded in a distorted single-bond geometry to one S2- atom. The Bi–S bond length is 2.82 Å. In the second Bi2+ site, Bi2+ is bonded to five S2- atoms to form a mixture of corner and edge-sharing BiS5 square pyramids. There are a spread of Bi–S bond distances ranging from 2.77–2.93 Å. In the third Bi2+ site, Bi2+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Bi–S bond distances ranging from 2.73–3.04 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 1-coordinate geometry to two Bi2+ atoms. In the second S2- site, S2- is bonded in a 1-coordinate geometry to four Bi2+ atoms. In the third S2- site, S2- is bonded in a distorted single-bond geometry to five Bi2+ atoms.