The silver cuprate AgCuO2 powder was prepared by a chemical co-precipitation method and characterized by XRD, SEM and TEM techniques. The electrochemical behaviors of AgCuO2 electrodes and AgCuO2 modified by sulfur were studied by means of galvanostatic discharge and line sweep voltammetry experiments. The results indicated that the specific capacity of AgCuO2 could reach 422.32 mAh·g-1 at middle discharge rate and the addition of sulfur could significantly improve the discharge performance of AgCuO2. The mechanism for this modified effect was also discussed.