Thermal analyses of the mixture of MgH(2) and LiBH(4) doped with TiCl(3), and each element MgH(2) or LiBH(4) doped with TiCl(3) were performed under an inert gas flow and 0.5 MPa H(2)-gas conditions. It was indicated that the hydrogen desorption reaction of MgH(2) + 2LiBH(4) to MgB(2) + 2LiH + 4H(2) phases proceeded at temperature above 400 degrees C under 0.5 MPa hydrogen, whereas, under an inert gas atmosphere, the reaction of the same mixture was transformed into Mg + 2B + 2LiH + 4H(2) phases in a temperature range from 350 to 430 degrees C. Before these reactions, the dehydrogenation of MgH(2) and the melting of LiBH(4) took place under both hydrogen and the inert gas atmospheres with increasing temperature. In addition, the molten LiBH(4) did not decompose into LiH, B and H(2) below 450 degrees C under 1 MPa H(2), while the LiBH(4) decomposed even below 450 degrees C under an inert gas atmosphere. From these results, it is deduced that the reaction producing MgB(2) is a solid-liquid reaction between solid Mg and liquid LiBH(4) above 400 C without decomposition of molten LiBH(4) Under a hydrogen atmosphere, while MgH(2) dehydrogenate. A characteristic solid-liquid reaction is realized under a hydrogen atmosphere for proceeding of the MgB(2) producing reaction in this system. (C) 2007 Elsevier B.V. All rights reserved.