Oxides precursors ZrxTi1−xO2(x=0.22, 0.39, and 0.60) were prepared by a hydrolytic sol–gel process. The amorphous mixed oxides are homogeneous as deduced from electron microscopy and XPS studies. The crystallization of these amorphous oxides was studied by TGA–DTA and thermodiffractometry. Quantitative analysis of the crystalline phases, obtained at 1000°C, was carried out by the Rietveld method. The samples are mixtures of TiO2, Zr5Ti7O24, and ZrO2oxides, and the stoichiometry of the stable zirconium titanate phase was found to be Zr5Ti7O24and not ZrTiO4(=Zr6Ti6O24). In this work, the power of Rietveld refinements to determine phase ratios of very related (and thus very overlapped) phases is shown.