In this work, we study some aspects of self-structuring of Li2O-B2O3 and Li2O-B2O3-MoO3 molten media depending of the composition, temperature, starting materials, etc. and comment them within the frames our model concepts. The main results were obtained by the methods of spectroscopy of glasses, whereas complementary results, by in situ diffractometry and spectroscopy of melts and quantum-chemical calculations. These results are compared with our practice on growing LiB3O5 single crystals and some recommendations are given concerning the procedure. It is shown that the application of a rather simple spectroscopic testing for the sample of borate molten media can be useful for improving the technology of growth of large single crystals for practical use. (c) 2006 Elsevier B.V. All rights reserved.