In the presence of 1,12-diaminododecane (DADD), tetragonal ZrO2 nanoparticles (ca. 10 nm) with high phase purity (monoclinic volume content: less than 0.1) and large surface area (100 m(2)/g) and pure monoclinic ZrO2 nanorods (aspect ratio of ca. 10) have been successfully prepared upon hydrothermal processing at 230 degrees C for 3 days of zirconyl nitrate-derived hydrous zirconia gels at different pH values. The complementary data from FFIR, Raman, TGA/DTG confirm the presence of hydrocarbon fragments (1-3 wt%) on the surface of DADD-derived zirconia nanocrystals. These organic residues account for their features in the phase composition, particle size and morphology, and surface wettability. (C) 2006 Elsevier Ltd. All rights reserved.