Crystal structures have been determined from X-ray diffraction data for [Hpy]₂[Sb₂OBr_nCl_6-n] where n= 0 (1), 2 (2), and 4 (3) and Hpy = pyridinium. The compounds are isostructural, crystallising in the monoclinic space group P2₁/c, with the following cell dimensions: a= 8.816(3), b= 8.61 5(3), c= 28.116(8)Å, β= 112.73(5)° for (1); a= 8.91 9(3), b= 8.81 3(3), c= 28.21 8(8)Å, β= 113.57(4)° for (2); and a= 8.982(3), b= 8.884(3), c= 28.343(8)Å, β= 113.80(4)° for (3). The structures have been solved by Patterson and Fourier methods and refined by full-matrix least squares to R 0.074 (2 652 observed reflections) for (1), 0.075 (2 887) for (2), and 0.066 (2 706) for (3). The compounds all contain a discrete [Sb₂OX₆]^2– anion in which the antimony atoms are triply bridged by one oxygen and two halogen atoms. Both (2) and (3) show halogen disorder. In the former, all six halogen positions are involved but the two bridging positions have ca. 53% occupancy by bromine; in (3) the disorder is between the two sets of terminal positions and the bridging positions are uniquely occupied by bromine. A major feature of the structures and probably a great contributor to the overall stability is a very strong hydrogen bond [2.68(1)Å in (1) and 2.72(1)Å in (2) and (3)] between the bridging oxygen and one of the pyridinium cations.