Self-assembled monolayers (SAMs) formed from biphenyl-4-ol (BPOH) and p-terphenyl-4-ol (TPOH) on hydrogenated Si substrates were characterized by X-ray photoelectron spectroscopy and angle-resolved near-edge X-ray absorption fine structure spectroscopy. Both aromatic molecules were found to form well-oriented and densely packed films. The packing densities of the aromatic moieties in BPOH/Si and TPOH/Si are quite similar, and the effective film thickness is equal to 10.9 and 15.1 Angstrom, respectively. The average tilt angles of the aromatic backbones in BPOH/Si and TPOH/Si were estimated as 28.7degrees +/- 5degrees and 33degrees +/- 5degrees respectively, which are only slightly larger than the analogous values for the thioaromatic SAMs of the same chain length on noble metal substrates.