Preparation of lithium ion conducting solid electrolytes in the composition 75Li(2)S . xP(2)S(3) . (25 - x)P2S5 (mol%) was attempted by use of a high-energy ball-milling process at room temperature. Amorphous samples were obtained in the composition range of x = 0 to x = 5. In the samples with x greater than or equal to 8.3, a crystalline Li2S phase was remained after the ball milling for 50 It. The lithium ion conductivity at 298 K of the amorphous samples was increased with an increase in x, and the amorphous sample with x = 5 showed the highest lithium ion conductivity of 6.2 x 10(-4) S . cm(-1) at 298 K among the obtained samples. A laboratory-scale all-solid-state lithium battery using the amorphous sample with x = 5 showed good discharge-charge performance at room temperature. (C) 2004 Elsevier B.V. All rights reserved.