A multimetal oxide of the formula I Aga−bMbV2Ox*c H2O,  I where M is a metal selected from the group consisting of Li, Na, K, Rb, Cs, Tl, Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pb, Cr, Au, Al, Fe, Co, Ni and/or Mo, a is from 0.3 to 1.9 and b is from 0 to 0.5, with the proviso that the difference (a−b)≧0.1 and c is from 0 to 20 and x is a number determined by the valence and amount of elements different from oxygen in the formula I, has a crystal structure giving an X-ray powder diffraction pattern which displays reflections at the lattice spacings d of 15.23±0.6, 12.16±0.4, 10.68±0.3, 3.41±0.04, 3.09±0.04, 3.02±0.04, 2.36±0.04 and 1.80±0.04 Å. Precatalysts and catalysts produced therefrom for the partial oxidation of aromatic hydrocarbons are also provided.