A planar, triangular triphenylboroxine molecule is obtained from three benzeneboronic acid molecules by releasing water upon heating. Thin films of triphenylboroxine were prepared on inorganic substrates by vacuum-deposition, and they were found to evaporate comparatively quickly in air. The evaporation process was investigated in air and in Ar by atomic force microscopy (AFM) and transmission electron microscopy (TEM). A thin film of triphenylboroxine on muscovite remained with no change for 6 It in an Ar atmosphere, while it gradually disappeared in air. Thin films grown on graphite disappeared both in Ar and air, but more rapidly in air. These findings suggest that triphenylboroxine in the thin films decomposes to benzeneboronic acid in the presence of water in air and then evaporates. Electron diffraction patterns of a thin film of triphenylboroxine on graphite show that crystallites grow epitaxially with respect to graphite and exhibit a polymorph. The difference between crystal structures in a thin film and bulk may cause different evaporation processes. (C) 2002 Elsevier Science B.V. All rights reserved.