Self-assembled monolayer of 2,2′:5′,2″-terthiophene-5-methanethiol (5mTP) on Au(111) has been investigated with synchrotron-based X-ray photoelectron spectroscopy (XPS) and carbon K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy. XPS data show that 5mTP bonds to Au(111) via an SH bond cleavage while leaving the terthiophene intact. The binding energies of S 2p 3/2 core levels for thiolate and terthiophene are located at 162.1 and 163.8eV, respectively. The broad C 1s core level is centered at a binding energy of 285.2eV. Intensity analysis of the S 2p peaks reveals a preferential alignment of the terthiophene with its long axis oriented near the surface normal. Carbon K-edge NEXAFS spectra show the presence of sharp, polarization-dependent, 1s→π * resonances located at energies of 285.60 and 287.54eV. From the E-vector polarization analysis, the aromatic plane of the 5mTP is concluded to be tilted at 25° from the surface normal.