The preparation of CeO2-ZrO2 mixed oxides preparation was studied by evaluating the influence of several conditions. Coprecipitation was taken as the standard method and the effects brought about by the cerium salt precursor ((NH4)(2)Ce(NO3)(6) or Ce(NO3)(3)), the introduction of drying and aging steps as well as pH controlling upon precipitation were analyzed. The samples were characterized by X-ray diffraction, Raman spectroscopy, temperature-programmed reduction, infrared spectroscopy, oxygen storage capacity and surface area. The use of Ce(NO3)(3) leads to the formation Of c-CeO2 and t-ZrO2 mixed oxide whereas a solid solution is achieved by using (NH4)(2)Ce(NO3)(6). It was observed that the cerium precursor is the most significant parameter of preparation procedure since it defines the crystalline phases and consequently the reducibility behavior of the CeO2-ZrO2 system. © 2004 Elsevier B.V. All rights reserved.