Oxidation of solid and liquid zinc by water (temperature 335-648 degrees C, pressure 13.7-31.2 MPa, water density 0.045-0.420 g/cm(3)), supercritical CO2 (514-600 degrees C, 7.1-24.4 MPa, 0.041-0.158 g/cm(3)), mixture of H2O/CO2 (140-600 degrees C, 30 MPa, water density 0.026-0.569 g/cm(3), initial ratio of [H2O](0)/[CO2](0) has been studied. On the basis of scanning and transmission of electron microscopy data, we have demonstrated that depending on the process conditions nanoparticles with the size of 2-100 nm, nanorods and nanowhiskers with the diameter of 10-100 nm and length of up to 50 mu m, mechanically solid nanostructured ceramics are synthesized. The presence of (Zn)(n) clusters with the size below 5 nm has been found in ZnO nanoparticles synthesized in supercritical water and H2O/CO2 mixture. Higher level perfection of nanocrystals formed at zinc oxidation by subcritical water has been revealed by means of room temperature photoluminescence study. (C) 2008 Elsevier B.V. All rights reserved.