The solid solubility and diffusion of plutonium in aluminum were studied at 600 deg C. Cylindrical diffusion couples were prepared by coextrusion, and consisted of a core of 7 wt.% plutonium-93% aluminum alloy clad with aluminum. Quantitative autoradiography was utilized to determine the solid solubility, while metallographic measurement furnished data for calculation of a dlffusion coefficient. (auth)