Curing (digestion) of hydrous zirconia in its mother basic solution at elevated temperatures increased the surface area and thermal stability of the zirconia powders. However, the curing studies on ZrO2 performed by previous researchers were ambiguous because Si could dissolve from the glass container in basic condition during curing, thereby enhancing the surface area and thermal stability of ZrO2 powders. In the current study the effects of curing and Si doping were separated by Curing hydrous zirconia in a Teflon flask and by doping with different amounts of tetraethylorthosilicates (TEOS) solutions (0-10.9 wt.% Si in ZrO2). We found that curing did increase the pore volume and the pore size of ZrO2 powders but had negligible effect on the surface area of zirconia after 4 h of heat treatment at elevated temperatures. Si doping was found to significantly increase the surface area, delay the crystallization, stabilize the tetragonal phase of ZrO2 and retard the crystallite growth. Curing was found to have a significant effect on the surface area of Si-doped ZrO2. (C) 2003 Elsevier B.V. All rights reserved.