A solid-electrolyte secondary cell comprising a positive and a negative electrode composed of a copper chevrel compound (Cu.sub.x Mo.sub.6 S.sub.8), and copper ion conductive solid electrolyte is provided. This secondary cell is capable of charging with a current as high as about 1 mA/cm.sup.2, can stand high temperatures of up to 100.degree. C. and maintains its initial performance even after long-time charging and discharging. A cell small in voltage drop during dicharge is also provided by using a heat treated mixture of a copper chevrel compound and a copper ion conductive solid electrolyte represented by the formula K.sub.q Rb.sub.1-q Cu.sub.4 I.sub.2-p Cl.sub.3+3 (0.ltoreq.q.ltoreq.0.5, 0.25.ltoreq.p.ltoreq.1.0) for both positive and negative electrodes.