The 70Li(2)S center dot 30P(2)S(5) (mol%) glasses were prepared by quenching melts held at different temperatures and the glass-ceramics were prepared by crystallization of these glasses. It was clear that the local structure of the glasses changed by the melting temperature. The increase in melting temperature from 750 to 900 degrees C led to form the P2S64- ions, which would promote the crystallization of Li4P2S6 phase with low conductivity. The superionic Li7P3S11 metastable phase was precipitated by crystallization of the glass prepared from the melt at 750 degrees C. The obtained glass-ceramic showed high lithium ion conductivity of 2.1 x 10(-3) S cm(-1) at room temperature. The lithium ion transport number of the glass-ceramic was almost unity. (C) 2007 Elsevier B.V. All rights reserved.