The crystal structure of the displacive ferroelectric mineral russellite, Bi₂WO₆, has been determined using Rietveld profile refinement of high-resolution, time of flight, neutron powder diffraction data on the synthetic compound. Russellite is orthorhombic, Pca2₁, with a 5.43726(2) Å, b 16.43018(5) Å , c 5.458422) Å, Z = 4 and is isostructural with the bismuth molybdate mineral koechlinite, Bi₂MoO₆. The structure consists of layers of tilted WO₆ octahedra sandwiched between layers of bismuth and oxygen with the tungsten displaced from the centre of the octahedron by 0.278 Å.The orientations of the lone-pair electrons in the Bi³⁺ cations have been inferred from the 3.0 Å coordination shells of both crystallographically independent bismuths, and have been found to be non-centrosymmetric, an effect which may give rise to the tilting of the WO₆ octahedra. New laboratory source X-ray powder diffraction data are presented for russellite, which, with supplementary synchrotron powder diffractometry, corroborate the new space group and structure determination.