The morphological evolution and nature of the degradation of the moisture-exposed tris(8-hydroxyquinoline) aluminum (Alq(3)) thin films have been microscopically investigated by variable-temperature tapping mode atomic force microscopy and complementarily by thickness-shear mode acoustic wave sensor. It is plausibly ascertained that the dark hole in the Alq(3) films results from the release of the volatile 8-hydroxyquinoline, a product of the reaction of Alq(3) with moisture. (C) 2003 Elsevier Science B.V. All rights reserved.