The hydrothermal reaction of a mixture of Na2MoO4 center dot 2H(2)O, V2O5, pyromellitic acid (1,2,4,5-C6H2(COOH)(4)), (C2H5)(4)NCl and 0,1 M H2SO4 for 88 h at 180 degrees C gives blue needle-like crystals of [(V2O2)-O-IV(H2O)(2) (C6H2(COO)(4))] in 20% yield (based on V) and dark blue prismatic crystals of the title compound, mixedvalance (N(C2H5)(4))(4)[VMo12V2O44], 1, in 12% yield (based on Mo). I was investigated by means of elemental analysis, thermogravimetry, Fourier Transform Infrared Spectroscopy and Single Crystal X-ray Diffraction Methods. Crystal data for the compound: monoclinic space group P2(1)/c (No:14), a=13.7815(12) b=13.0271(9) c= 21.189(2) angstrom, beta= 113.909(7)degrees, Z=2. Although [XM14O42](-n) (X=P, Si, Ge, V and M=Mo and/or V) cores have been previously determined, this is the first time that [VMo12V2O44](-4) core is synthesized and characterized. The structural difference between I and these HPOMs is the coordinational geometry of the central metal atoms. The central vanadium in I has an octahedral coordination geometry, whereas in literature, the central V, P, Si and Ge atoms in [V15O42](-9) / [SiM8V6O42](-4)/[PM8V6O42](-5) / [GeM8V6O42](-4) have tetrahedral coordinational geometry. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.