Introduction of branched alkyl chains at the terminal positions of sexithiophene drastically improves the Solubility of the compound, while still maintaining satisfactory charge carrier mobility. Field-effect transistors based on spin-coated films of the sexithiophene derivative exhibited p-type characteristics. Post thermal treatment enhanced crystallinity of the films and afforded a field-effect mobility of 0.11-0.18 cm(2) V-1 s(-1) and an on/off ratio of 10(4).