C(60) field-effect transistors (FETs) have been fabricated with parylene gate dielectric on Si/SiO(2), on polyethylene terephthalate, and commercially available transparent sheet substrates. The best performance of the C(60) FET device is achieved with parylene as gate dielectric: field-effect mobility of 0.41 cm(2) V(-1) s(-1) and on-off ratio of similar to 10(7). The excellent FET characteristics are recorded without any annealing, and the devices were kept in He atmosphere after an exposure to air. This result suggests the parylene gate dielectric to be highly H(2)O repellent. The mechanical flexibility and air-exposure effect were studied for the C(60) FET with parylene gate dielectric. (C) 2008 American Institute of Physics.