The characteristics of the solid electrolyte cells and have been studied. The open‐circuit voltages of these solid electrolyte cells were 0.217V and 0.265V, respectively, at 20°C. These cells could discharge in the temperature range of −75° to 150°C. Only a small polarization was observed at relatively high current density discharge. Diffusion coefficients of Ag in these systems were also evaluated from the time‐ dependent behavior of the cell voltage as a function of current density.