The electrical and electrochemical properties of the 70Li(2)S center dot(30-x)P2S5 center dot xP(2)O(5) glass-ceramics were investigated. The glass-ceramics with up to 5 mol% of P2O5 kept high conductivity over 10(-3) S cm(-1). The 70Li(2)S center dot 27P(2)S(5)center dot 3P(2)O(5) glass-ceramic exhibited the highest conductivity of 3.0 x 10(-3) S cm(-1) at room temperature and the lowest activation energy of 16 W mol(-1) for conduction. Electrochemical stability of the glass-ceramic was improved by substituting 3 mol% of P2O5 for P2S5 because the oxygen-incorporated Li7P3S11 crystal would be precipitated in the glass-ceramic. The all-solid-state cell using the 70Li(2)S center dot 27P(2)S(5)center dot 3P(2)O(5) oxysulfide glass-ceramic worked as a lithium secondary battery at room temperature. (C) 2008 Elsevier B.V All rights reserved.