Fusion method is used to prepare alpha-PtO2 and has a special needle-like microcrystalline morphology, with a diameter of ca. 6 nm and a length of ca. 50 nm. The two Pt-O bonds of alpha-PtO2 are different in strength and alpha-PtO2 decomposes thermally to Pt-0 in two steps. alpha-PtO2 is a p-type oxide semiconductor with a band-gap of 1.84 eV alpha-PtO2 is easily reduced by ethanol, its reduction product, Pt-0, can directionally catalyze the oxidation of ethanol to acetic acid in the presence of air, while acetaldehyde, acetal and ethyl acetate are intermediates. (C) 2002 Elsevier Science B.V. All rights reserved.