Electrochemical stability of a fullerene (C-60) thin film supported on Au(111) was investigated in an ionic liquid electrolyte, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([C(4)mpyrr][Tf2N]). The prepared thin film of C-60 was characterized by atomic force microscopy and scanning tunneling microscopy, which revealed homogeneous epitaxial growth with approximately 40 layers. The six successive redox states of C-60 were clearly observed at room temperature by cyclic voltammetry (CV) at scan rates faster than 100 mV s(-1), whereas they were hardly seen at the scan rate of 2 mV s(-1). Elevated temperature in [C(4)mpyrr][Tf2N] led to a significant decrease in the redox currents for each redox state of C-60(n) (n = 1-6) in the CV profile with increased scan cycles. The obtained result indicates that the dissolution of the C-60 film is caused by cation insertion and accelerated by the generation of multiple redox states of C-60(n) during the continuous scans. The redox states of C-60 in [C(4)mpyrr][Tf2N] can be clearly controlled by the scan rate and temperature. The diffusion coefficient, heterogeneous rate constant, and activation energy (D, E-a,E-k, and k degrees, respectively) of the C-60 /C-60 redox couple were evaluated by CV simulation. (C) 2016 Elsevier Ltd. All rights reserved.