The crystal structure of Ni 4 V 3 O 10 was initially solved using the parallel tempering global optimization algorithm in FOX with the 11-BM X-ray powder diffraction data. Rietveld refinements to X-ray and neutron powder diffraction data were performed with GSAS-II. The Bilbao Crystallographic Server's PSEUDO program guided crystallographic space group determination, and the server's MAXMAGN program provided the maximal magnetic space groups for Ni 4 V 3 O 10 . VESTA was used for bond valence sum analysis of vanadium oxidation states, for crystal structure images, and for magnetic space group images. Bond valence sum parameters came from analysis by Brown and Altermatt and by Liu and Thorp, and the B parameter was set at 0.37 Å based on their analysis. For all BVS calculations, nickel and oxygen had fixed oxidation states of +2 and -2, respectively.