Pentacene transistors and integrated circuits on flexible substrates (see Figure) have been fabricated with gate electrodes prepared using a purely additive process combining microcontact printing and selective electroless plating. The printed metal patterns have a resolution of better than 5 mum. Transistors have a carrier mobility of 0.06 cm(2) V-1 s(-1) and an on/off current ratio of 10(6). Ring oscillators have a signal propagation delay of 170 mus per stage.