A field-effect transistor (FET) device was fabricated with thin films of C-2v isomer of Pr@C-82. This device apparently showed n-channel normally on type FET properties, where non-zero current was observed at the gate-source voltage, V-GS, of 0 V. Normally off FET properties were observed by subtraction of the non-zero current from the drain current. Thus the normally on properties are ascribed to the high bulk current caused by the small energy gap of approximate to 0.3 eV. The field-effect mobility for this FET was 1.5 x 10(-4) cm(2) V-1 s(-1) at 320 K, being comparable to those of other endohedral metallofullerene FET devices. (c) 2005 Elsevier B.V. All rights reserved.