[en] The kinetics of the dissolution of plutonium metal in sulfamic acid at varying temperatures was determined. Hydrogen off-gas rates and plutonium concentrations were determined as functions of time for different dissolving conditions. Nominal 2.2 kg Pu buttons (surface area, 171 cm²) should yield solutions containing 190 to 260 g Pu/L and 3.3M sulfamate ion after a one-hour dissolving time at 70⁰C. Hydrogen off-gas rates were calculated to vary from a high of 2.7L of gaseous hydrogen per minute (STP) at the beginning of a dissolving cycle to 50 mL of hydrogen gas per minute at the end of a one-hour dissolving time. Sludge formation, which is a problem at ambient temperatures, does not occur at dissolving temperatures of 60 to 80⁰C. Dissolution curves suggest that the mechanism of dissolution changes at about 50 to 55⁰C. Below this temperature, a surface coating of plutonium hydride may form; above this temperature, plutonium metal appears to be converted directly to Pu³⁺. 13 figures, 1 table