PROTON-CONDUCTING SOLID ELECTROLYTE, ELECTROLYTE LAYER, AND BATTERY

What is provided are a proton-conducting solid electrolyte which can exhibit high proton conductivity and stability in a low-temperature range and a medium-temperature range, an electrolyte layer formed of the proton-conducting solid electrolyte, and a battery. As an example, a proton-conducting solid electrolyte represented by a general formula: BaScMoOH, in which α is −0.2 to 0.2, x is 0.1 to 0.3, y is 0 to 1-3x, and δ is 0 to ½-3x/2, a proton-conducting solid electrolyte represented by a general formula: BaScMoOH, in which x is 0.15 to 0.25, y is 0 to 1-3x, and δ is 0 to ½-3x/2, or the like; an electrolyte layer, and a battery are provided.