The present paper deals with the catalytic decomposition of SO3 reaction. Cu/Fe/Ti/Al2O3 composite granule catalysts prepared by a combination of Yoldas process and oil-drop method were studied in an attempt to find some suitable catalysts for the decomposition of sulfur trioxide as the oxygen-generating reaction in the thermo-chemical water splitting process. CuFe/Ti:Al-1:2 shows high SO3 conversion (69%) at 800 A degrees C compared with other catalysts because of the high surface area and the support permitted a better dispersion of Ti.