The redox property of Sc-3@C-82 is investigated by using disifirane as a chemical probe. The redox potential of Sc-3@C-82 in o-dichlorobenzene shows a high reactivity attributable to its high electron-accepting and -donating ability. No ESR signal is observed at room temperature for Sc-3@C-82 in the presence of pyridine, indicating formation of the diamagnetic Sc-3@C-82 anion. The diamagnetic Sc-3@C-82 anion is also prepared electrochemically in 1,2-dichlorobenzene. (C) 2004 Elsevier B.V. All rights reserved.