Mechanical mixtures of zirconia xerogel and crystalline Y2O3 were hydrothermally treated by microwave and traditional route, respectively. Some mixtures were used either as powders form or as cylindrical compacts isostatically pressed at 150 MPa. The microwave-hydrothermal treatments were performed at 110, 150 and 200 degrees C for reaction times up to 2 h, whereas the traditional hydrothermal treatments were performed at 110 degrees C at increasing reaction times up to 7 days. All the treatments were performed in the presence of diluted (0.2 M) or concentrated (2.0 M) solution of (K2CO3 + KOH) mineralizer. The crystallization-stabilization mechanism of synthesized Y-based zirconia powders and the reaction times for the full crystallization at the low temperature of hydrothermal treatments are discussed. (c) 2005 Elsevier B.V. All rights reserved.