Effect of annealing temperature on luminescence of Eu3+, ions was studied in nanocrystal zirconia prepared by co-precipitation. The XRDs reveal with annealing temperature increasing the tetragonal crystal phase of the samples is stable. The emission spectra show the strong emission at 595 and 604 nm at 394 nm excitation. Under continuous UV (394 nm) irradiation the 604 nm emission intensity changes of the samples show as a function of irradiation time. In addition, the charge-transfer states of the samples are affected by the annealing temperature. These are associated with the defects allin the surface of the nanocrystalline ZrO2 with Eu3+ ions. (c) 2006 Elsevier B.V. All rights reserved.