The generation of essentially pure hydrogen through a redox cycle using methane and then water has been investigated for a series of tungsten oxides stabilised by ceria-zirconia. The calcined starting materials were largely monoclinic WO(3) with CeO(2) and ZrO(2) undetectable by XRD. Samples containing 80% and especially 69% WO(3) showed additional XRD lines due to a phase of unknown composition. Temperature programmed reduction to 750 degrees C in methane converted samples containing WO(3) alone to WC together with small amounts of tungsten metal and a WC(1-x) phase. Reoxidation in water at the same temperature then produced CO and H(2) in corresponding amounts. Under the same conditions the 69% WO(3) sample was reduced only as far as WO(2) and reoxidation yielded H(2) largely free of CO. The reoxidation product was not WO(3) but consisted of various non-stoichiometric oxides with composition WO(2+x) (x = 0.72, 0.83, etc). The reduction-reoxidation cycle could be repeated many times without loss of hydrogen production efficiency. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.