Two conjugated polymers, IIDDT and IIDT, based on an isoindigo core were developed for organic field-effect transisitors. Investigation of their field-effect performance indicated that IIDDT exhibited air-stable mobility up to 0.79 cm(2) V(-1) s(-1), which is quite high among polymer FET materials. The facile preparation and high mobility of such polymers make isoindigo-based polymers very promising for application as solution-processable organic semiconductors for optoelectronic devices.