Marinobacter sp.MnI7-9 efficiently oxidizes Mn2+ to generate biogenic Mn oxide (BMO), primarily δ-MnO2.In this study, we show that the BMO has a high adsorption capacity for Ag+ compared to the chemical MnO2 (CMO), especially at high concentrations of Ag+.The maximum adsorption capacities of the BMO and the CMO at 28℃ were 8.097 and 0.787 mmol/g, respectively, which correlates well with both the pseudo-second order model and the Langmuir model.The change in enthalpy (△Hθ) for the BMO was 59.692 kJ/mol, indicating that it acts primarily by chemical adsorption, while △Hθ for the CMO was 2.287 kJ/mol, which suggests a physical adsorption process.All of the △Hθ values were greater than zero, indicating an endothermic adsorption process.The values for the change in free energy (△Gθ) using both the materials were all negative, which suggests that the adsorption occurs spontaneously.Adsorption by the BMO and the CMO was driven by entropy based on the positive △Sθ values.After adsorption, the silver remained on the surface of the BMO and primarily took the form of Ag (Ⅰ).An ideal desorption method using nitric acid was established and recovered 100% Ag.