In this letter, the integration of a high-κ gate dielectric has been demonstrated for achieving low-operating-voltage organic field-effect transistors (OFETs) and circuits based on solution-processed poly(3-hexylthiophene) (P3HT). We have successfully demonstrated all-p-type organic circuits based on P3HT operating at below 4 V supply voltage. The switching behavior is improved by using the bootstrapping technique, with the bootstrapped inverter showing good results with a dc gain (Av) of -1.7 and VOH and VOL values of 3.3 and 0.35 V, respectively. The output swing of the bootstrapped inverter is improved by about 40% when compared to that of simple all-p-type inverters, as demonstrated by using experimental characterizations. © 2009 IEEE.