We report the effect of the conductivity of the gate electrode on operation speeds in printed organic ring oscillators (RO). The highly conducting gate electrode leads to a superior oscillation frequency (as high as similar to 30 kHz) for the printed ROs. Above the optimum thickness of the gate electrodes (similar to 30 nm), inkjet-printed p-type poly(3-hexylthiophene) (P3HT) and n-type poly([N, N-9-bis(2-octyldodecyl) naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)) (P(NDI2OD-T2)) organic field-effect transistors showed reasonably high hole and electron mobilities of similar to 0.05 cm(2) V-1 s(-1) and similar to 0.25 cm(2) V-1 s(-1), respectively. Complementary inverters and ring oscillators based on these p-and n-type semiconductor transistors were constructed, where the inverters showed the inverting voltage, (V-inv) near the ideal switching points at 1/2 the drain voltage (V-DD), high gain (similar to 10), low static power consumptions, as well as high noise margin (similar to 60% of 1/2V(DD)). Finally, printed P3HT complementary ring oscillators with a gate thickness over 30 nm exhibited the highest oscillation frequency (similar to 30 kHz). (C) 2013 Elsevier B.V. All rights reserved.