The phosphor LaInO3:Eu3+ exhibits, in addition to the weak orange-red emission of Eu3+, a broad blue emission whose origin formed the basis for the reinvestigation of luminescence of LaInO3 and the analogous LaGaO3, well known host lattices for luminescent centers. The results are analyzed based on the luminescence observed for In3+ and Ga3+ in various host lattices. An attempt is made to understand the mechanism of the luminescence of d(10) ions In3+ and Ga3+. (c) 2005 Elsevier Ltd. All rights reserved.