The properties and structure of the lithium ion-conducting oxysulfide glasses in the systems Li2S-SiS2-LichiMOgamma (LichiMOgamma: lithium ortho-oxosalt, M = Si, P, Ge, B, Al, Ga and In) are reviewed. The Li2S-SiS2 glass added with small amounts of LichiMOgamma exhibited high glass stability against crystallization, high conductivity of 10(-3) S cm(-1) at room temperature, and wide electrochemical window. Further addition of Li-chi,MOgamma reduced these superior properties in any system. High-resolution solid-state NMR and X-ray photoelectron spectroscopy revealed that the silicon atoms coordinated with both bridging oxygen atoms and nonbridging sulfur atoms were mainly present in the glasses with small amounts of LichiMOgamma. The presence of these unique structural units brought about high conductivities and high thermal stability of these glasses. The solid state battery with the oxysulfide glass worked as a lithium secondary battery and performed excellent cycling behaviors.