Tetragonal yttrium-stabilized zirconia samples were obtained by pyrolysis of amorphous acetates containing both metals, at 950 °C in air. The dilatometric behaviour of samples indicates a dedensification when pyrolysis is carried out with a non-linear heating rate causing an absence of fine open porosity. A destabilization when cooling is observed for samples exhibiting a wide granulometry with agglomerate sizes reaching 100 μm. Even when neither one, nor the other phenomenon is noticed, an important aggregation state of the starting powders limits the densification and leads to poor sintered densities.