UV 10 ns nitrogen laser pulses at 337 nm give substantial shift of energy gap for LiB(3)O(5) (LBO) nanocrystals (NC) with sizes below 200 nm. The mechanically prepared powders of the NC were put between the MgF(2) UV-transparent windows. The power density of the UV-photoinducing beam was varied up to 2.1 GW/cm(2). The mechanically prepared LBO NC possessed the sizes varying within the 120 nm-350 nm. The effect exists only for the NC below 190 nm. The photoinduced changes disappeared after about 180 s of switched off of the photoinduced UV beam. For the NC sizes below 125 nm the observed red shift is significantly less. (c) 2010 Elsevier B.V. All rights reserved.