Large-scale synthesis of crystalline MgO nanobelts was achieved through a simple thermal evaporation method. The products consist of a large quantity of single-crystalline MgO nanobelts with the cubic structure. A strong and broad green emission band centered at 508 nm and a weak ultra-light emission band centered at 383 nm were observed in the photoluminescence spectrum of the MgO nanobelts, which is attributed to the singly ionized oxygen vacancies in the MgO nanobelts. Another red-light emission band centered at 721 mn was also observed, which may be assigned to the relaxation luminescence of defect centers in the MgO nanobelts. (C) 2002 Elsevier Science B.V. All rights reserved.