Thin-film transistors with fullerene as n-type organic semiconductor have been fabricated. A polymeric gate dielectric, polymethyl methacrylate, has been used as an alternative to usual inorganic dielectrics. No significant differences in the microstructure of fullerene thin-films grown on polymethyl methacrylate were observed. Devices with either gold or aluminium top electrodes have been fabricated. Although the lower work-function of aluminium compared to gold should favour electron injection, similar field-effect mobilities in the range of 10(-2) Cm-1 V-1 s(-1) were achieved in both cases. Actually, the output characteristics indicate that organic thin-film transistors behave more linearly with gold than with aluminiurn electrodes. These results confirm that not only energy barriers determine carrier injection at metal/organic interfaces, but also chemical interactions. (c) 2006 Elsevier B.V. All rights reserved.