The Dy3+: PWO single crystal was subsequently annealed in air atmosphere at a temperature of 500degreesC, 550degreesC, 600degreesC, 700degreesC, 800degreesC, 900degreesC, and 1000degreesC, respectively. X-ray excited luminescence spectra were measured before and after each step of annealing. Annealing experiments confirmed the energy transfer-taking place from PbWO4 (PWO) host to Dy3+ ions, followed by the enhancing characteristic emission of Dy3+ ions. In the process of annealing, the luminescence of PWO host was significantly reduced while that of Dy3+ was increased simultaneously. Annealing at a temperature below 700degreesC suppressed the blue luminescence of the PWO host and enhanced its green components, while the emission of Dy3+ is increased to some extent. Further annealing at higher temperature strongly reduced the luminescence of the PWO host, while the emission of Dy3+ was greatly increased. Interstitial oxygen O-i could play an important role in the luminescence. Annealing could modify the luminescence of Dy3+ ions in PWO, which may be useful in terms of some application purposes. (C) 2002 Elsevier Science B.V. All rights reserved.