The title compound, nona-niobium vanadium penta-cosa-oxide, was prepared by a solid-state reaction at 1198 K. It is isotypic with Nb9AsO25, Nb9PO25 and Ta9VO25. The structure consists of NbO6 octa-hedra (one with 4/m.. and two with m.. symmetry) and VO4 tetra-hedra (-4.. symmetry) sharing corners and edges to form a three-dimensional framework. This framework can be considered as a junction between ribbons made up from NbO6 octa-hedra and chains of NbO6 octa-hedra and chains of VO4 tetra-hedra. The V site shows half-occupancy, hence one half of the VO4 tetra-hedra is unoccupied. The structural differences with α-Nb9VO25, VOSO4, SbOPO4 and NbOPO4 oxides are discussed.