Chemical transport reactions using bromine or iodine yielded crystals of BiNi with a largely ordered distribution of nickel atoms on octahedral and trigonal bipyramidal interstices within the hexagonal packing of bismuth atoms. The observed superstructure of the NiAs or InNi₂ structure types is described in the monoclinic space group F 1 2/m 1 (No. 12) with lattice parameters a = 1412.4(1), b = 816.21(6), c = 2142.9(2) pm, and β = 90°. The pseudo-orthorhombic cell facilitates twinning along [100]. Some crystals show an additional threefold twinning along [001]. The phase width of BiNi ranges from the nickel poor to the nickel rich region. In the vicinity of the stoichiometric composition BiNi, this has only an effect on the occupation of a single nickel position in the crystal structure.