Pure hexagonal phase of ZnO nanocrystallites with the sizes of several nanometers were synthesized by low-temperature (180 degrees C) thermal decomposition in air of a "green" single-source inorganic precursor, ZnO2 nanocrystallites, which were derived from the hydrothermal reaction of Zn(AC)(2) and H2O2 in an alkaline aqueous solution (pH = 10.0) at 100 degrees C for 12 h, and characterized by powder X-ray diffraction (XRD), transmission electronic microscopy (TEM), UV-Vis absorption spectrum, and room temperature photoluminescence (RTPL) spectrum. The use of ZnO2 nanocrystallites as the precursor to ZnO has some advantages: easy preparation, low decomposition temperature, no unwanted by-products and free of pollution to both the target products and the environment upon thermal decomposition (ZnO2 = ZnO + 1/2O(2)) (c) 2005 Elsevier B.V. All rights reserved.