One of the effective methods of growing stoichiometric LiNbO3 single crystals is the high-temperature top-seeded solution growth from K2O-Li2O-Nb2O5 fluxes. The variation of the crystal composition was examined as a function of the K+ content of the flux. A series of DSC and X-ray diffraction measurements were performed in order to establish proper chemical and thermal conditions for the formation of the stoichiometric material. By the combination of these results with the crystal growth and composition measurements, it was possible to establish the temperature limit for the growth of stoichiometric crystals, and a compositional range concerning the K2O-Nb2O5-Li2O system that can he used. (C) 2002 Elsevier Science B.V. All rights reserved.