Compounds of the general formula RxVxW1-xO3.nH(2)O have been prepared from peroxide solutions using the sol-gel process. Of these compounds, three phases are orthorhombic: WO3.1.5H(2)O (a = 7.68(3) Angstrom, b = 13.81(5) Angstrom, c = 7.39(3) Angstrom) H0.08V0.08W0.92O3.1.2H(2)O (a = 5.208(3) Angstrom, b =: 10.607(9) Angstrom, c = 5.079(3) Angstrom), and H0.17V0.17W0.83O3.1.5H(2)O (a = 7.60(3) Angstrom, b = 13.86(5) Angstrom, and c = 7.37(3) Angstrom); and two phases (with x = 0.25 and 0.33; n = 1) are amorphous as probed by X-rays. The thermal properties, IR, and X-ray photoelectron spectra of the compounds synthesized have been studied. The scenario of phase relations of the H2O-H-WO3-V2O5 system has been proposed. (C) 2004 Elsevier Ltd. All rights reserved.