C-60 field effect transistors (FETs) with interfacial modifications of electrodes using endohedral fullerene, C-60/La@C-82-FETs, are reported. An FET operation is observed without any annealing processes even once the fabricated devices are exposed to air, which has not ever seen in the conventional C-60 FETs. Another improvement in the field effect mobilities is also observed with little change in the threshold voltage. The interfacial surface modifications on the electrodes using endohedral fullerene analogues with large number of carriers are effective in reducing the trapping levels at the interface between C-60 thin film surface and the gold electrodes. (C) 2004 Elsevier B.V. All rights reserved.