Glassy electrolyte for lithium or sodium ions conduction The present disclosure relates to the development and improvement of sodium or lithium-ion electrochemical devices, in particular to the development of a new glassy electrolyte comprising high ionic conductivity for batteries, capacitors, and other electrochemical devices comprising a solid electrolyte glass comprising the formula R3-2xMxHalO wherein R is selected from the group consisting of lithium or sodium; M is selected from the group consisting of magnesium, calcium, strontium or barium; Hal is selected from the group consisting of fluorine, chlorine, bromine, iodine or mixtures thereof; X is the number of moles of M and 0≤x≤0.01 and the solid electrolyte glass has a glass transition point.