Here, we present the results of a detailed characterization of rigid-rod thiolate adlayers on Au(111) made by self-assembly of organothiols containing a terphenyl backbone, namely, p-terphenylthiol (TPT, C6H5-(C6H4)(2)-SH) and p-terphenylmethanethiol (TPMT, C6H5-(C6H4)(2)-CH2-SH) on Au(111). The results of low energy electron diffraction measurements reveal the presence of long-range order for adlayers prepared from both molecules. From the body of data obtained by X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, near-edge X-ray absorption fine structure measurements, and scanning tunneling microscopy, a structure model for adlayers of TPT and TPMT on Au(111) is proposed.