The new complex vanadium oxide K2SrV3O9 has been synthesized and investigated by means of X-ray powder diffraction (XPD), electron microscopy and magnetic susceptibility measurements. The oxide has an orthorhombic unit cell with lattice parameters a = 10.1922(2) angstrom, b = 5.4171(1) angstrom, c = 16.1425(3),k, space group Pnma and Z = 4. The crystal structure of K(2)rV(3)O(9) has been refined by Rietveld method using X-ray powder diffraction data. The structure contains infinite chains built by V4+O5 square pyramids linked to each other via VO4 tetrahedra. The chains form layers and potassium and strontium cations orderly occupy structural interstices between these layers. Electron diffraction as well as high resolution electron microscopy confirmed the structure solution. Magnetic susceptibility measurements revealed an antiferromagnetic interaction with J of the order of 100 K inside the chains and no long-range magnetic order above 2 K. The origin of the magnetic exchange is likely a result of super-exchange interaction through the two VO4 tetrahedra linking the polyhedra with the magnetic V4+ cations. (c) 2005 Elsevier Ltd. All rights reserved.