Lithium-ion conducting solid electrolytes in the composition (100-x)Li3PS4-xLiAlS(2) (mol%) were prepared by the use of a high-energy ball-milling process at room temperature. Amorphous samples were obtained in the composition range of x = 0 to x = 13.1. In the composition of x >= 18.2, a crystalline Al2S3 phase remained in the samples which were ball-milled for 35 h. The lithium ion conductivity at 298 K of the obtained amorphous samples was increased with an increase in the compositional parameter x and showed the maximum at the compositional parameter x = 13.1 (86.9Li(3)PS(4) . 13.1 LiAlS2: sigma(298K) = 6.0 x 10(-4)S cm(-1) at 298 K). (C) 2012 Elsevier B.V. All rights reserved.