The electroplating of source-drain (S/D) electrodes on a flexible polyimide (PI) substrate was applied to the fabrication of staggered poly(3-hexylthiophene) (P3HT) organic thin film transistors (OTFTs). Au or Au/Ni bilayer S/D electrodes were additively electroplated into patterned SU-8 photoresist masks on Cu(seed)/Cr(adhesion) layers sputter-deposited on O-2-plasma-treated PI substrates. The electrical measurements of the fabricated OTFTs showed that their non-ideal output characteristics were similar to those predicted by the model of electrical transport by the space-charge limited current (SCLC), regardless of the surface preparations used for the Au S/D electrodes. (c) 2005 Elsevier B.V. All rights reserved.