We introduce a room temperature and solution-processible vanadium oxide (VOx) buffer layer beneath Au source/drain electrodes for bottom-contact (BC) organic field-effect transistors (OFETs). The OFETs with the VOx buffer layer exhibited higher mobility and lower threshold voltages than the devices without a buffer layer. The hole mobility with VOx was over 0.11 cm(2)/V with the BC geometry with a short channel length (10 mu m), even without a surface treatment on SiO2. The channel width normalized contact resistance was decreased from 98 k Omega cm to 23 k Omega cm with VOx. The improved mobility and the reduced contact resistance were attributed to the enhanced continuity of pentacene grains, and the increased work function and adhesion of the Au electrodes using the VOx buffer layer. (C) 2014 Elsevier B.V. All rights reserved.