Complementary metal-oxide-semiconductor (CMOS) inverter circuits were fabricated using solution-processed field-effect transistors (FETs); p-type FET of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and n-type FET of Li-doped ZnO. As the source/drain electrodes of these FETs, reduced graphene oxide (RGO) films were prepared also by the solution process. The fabricated CMOS inverter device showed the voltage gain of 10.