The formation of a self-assembled monolayer (SAM) with octadecyltrichlorosilane (OTS) and phenetyltrichlorosilane (PTS) on a molybdenum (Mo) surface and surface properties like surface energy, work function, and roughness were studied. From X-ray photoelectron spectroscopy (XPS) measurement, the native oxide of Mo was confirmed and this could react with trichlorosilane to form a SAM. The formation of OTS and PTS monolayers was confirmed and investigated using contact angle measurement, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy, and XPS. After formation of the SAM, Si-O bond formation was observed with a decreased intensity of the Mo-O bond with XPS. The effect of dipping time for the formation of SAM was monitored with FTIR peak intensity of OTS and PTS and also the change in surface energy. It was confirmed that in the SAM formation with OTS, the hydrophilic surface was transformed into a hydrophobic state, roughness was reduced, and the work function was increased about 0.1 eV. Pentacene thin film deposited on SAM-treated Mo gave a better crystallinity and the contact resistance of Mo-pentacene was reduced. (c) 2008 The Electrochemical Society.