ZnO nanocrystalline films have been prepared by sol-gel method. X-ray diffraction study revealed the wurtzite structure with a (002) texture. The films treated up to 500 degreesC showed very strong UV emission at 3.3 eV with no distinct visible emission in both cathodoluminescence (CL) and photoluminescence (PL) measurements performed at room temperature. UV emission intensity was found to depend on the grain size and crystal orientation. A broad green emission at 2.4 eV, observed only in PL but not in CL, for the films treated at higher temperatures (greater than or equal to700 degreesC), is found to be due to the antisite defects rather than conventional oxygen vacancies. (C) 2004 Elsevier B.V. All rights reserved.