The authors studied the organic thin-film transistor (OTFT) with a solution based dihexylquaterthiophene (DH4T) by ink-jet printing. The DH4T with 1.0 wt % solution in dichlorobenzene was used for printing of an active layer of OTFTs. In order to obtain a smooth and uniform film of DH4T, the substrate temperature was elevated to 60 degrees C and the printing was performed by an overlapping method. The OTFT on plastic exhibited an on/off current ratio of similar to 10(7), a threshold voltage of -0.25 V, a gate voltage swing of 0.45 V/decade, and a field-effect mobility of 0.043 cm(2)/V s in the saturation region.