The thermal decomposition of Y-Zr citric complexes prepared in ethylene glycol or in water medium is studied. The compositions of "aqueous" Y, Zr- and YZr complexes are determined and the corresponding IR spectra are analyzed. Proofs are put in concerning the mixed-metal nature of the complexes. Based on TG, DTG and DTA analyses as well as on some intermediates identified, certain schemes are proposed concerning the processes involved in the thermal decomposition of the complexes studied. The crystal structure, crystallites size, specific surface area and the morphology of the final yttria stabilized zirconia are determined; the influences of the preparation mode and of the precursors calcination temperature on the characteristics mentioned are studied. (c) 2005 Elsevier Ltd. All rights reserved.