Amorphous solid electrolytes in the system xLi(2)O-(1-x)(0.6Li(2)S-0.4P(2)S(5)) (with x = 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 and 0.4) have been prepared from a mixture of Li2O, Li2S and P2S5 using a mechanical milling technique at room temperature and in inert atmosphere. The oxysulfide powder mechanically milled for 80 h with x = 0.25 shows an ionic conductivity (sigma) of 2.5 x 10(-4) S cm(-1) at 300 K which is the highest in this series. The glass transition temperature (T-g) exhibits a minimum at x = 0.25. Constant volume molecular dynamics was done for all x. Structural and transport results from molecular dynamics (MD) simulation are described. Changes in structure with x and their influence on sigma and T-g are discussed. (c) 2006 Elsevier B.V. All rights reserved.