The layered crystalline solids with the general formula M-x M-1(z) 2(H2O)(x+z)- (VO)(1-x-z)PO4. nH(2)O (M-1, M-2 = trivalent Al, Cr, Fe, Mn; x, z = 0.04-0.15, n = 2-3) were prepared by refluxing V2O5 with aqueous solutions of phosphoric acid and M-1 and M-2 metal salts. Compounds were characterized by X-ray diffraction (XRD) and thermogrametric and differential thermal analysis (TG-DTA) techniques. The elementary cell of these compounds is tetragonal, with space symmetry group either P4/nmm or P4/n. The dependence of basal spacings on different relative humidities of atmosphere was followed. The hydration water of the as-prepared compounds depends on the nature and amount of the trivalent metals M-1 and M-2.