Chemical kinetics of dissolution of aluminum alloy 6061 was investigated for the processing of Pu-238 for deep space missions. The rate of dissolution was measured by the heat release and appeared to be controlled by the rate of release of Al(OH)(4)(-) from the metal surface. Rates of reaction were measured from 273 to 365 K, giving an activation energy of 72 +/- 13 kJ(mol Al)(-1) and a pre-exponential factor of 5 +/- 3 x 10(9) dm(3)mol(-1)min(-1). Minor alloying elements did not appear to affect the reaction kinetics. The average heat of dissolution was -360 +/- 70 kJ(mol NaAlO2)(-1). When extrapolated to an infinitely dilute solution of aluminum, kJ(mol NaAlO2)(-1).