Vapor-phase hydrodeoxygenation (HDO) of guaiacol was investigated over a commercial Pd/C (A) catalyst (Evonik) and Pd/C (B), Re/C and PdRe/C catalysts prepared by incipient wetness impregnation of Norit SX-1 G activated carbon. The Pd/C catalysts had equivalent dispersions after reduction at 300 degrees C; however, Pd/C (B) had very low dispersion after reduction at 400 degrees C. CO chemisorption, Re L-III edge extended x-ray absorption fine structure (EXAFS) spectroscopy, and high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM) of the Re/C catalyst after reduction at 400 degrees C evidenced the formation of supported Re clusters. EXAFS spectroscopy of the PdRe/C catalyst after in situ reduction at 300 degrees C indicated the presence of Pd nanoparticles and Re clusters; a 2.70 angstrom Pd-Re contribution was required to adequately fit the Re L-III EXAFS spectrum. HAADF-STEM with energy-dispersive x-ray (EDX) analysis of the PdRe/C catalyst after reduction at 400 degrees C revealed Re clusters and Pd nanoparticles, some in intimate contact. In guaiacol HDO at 300 degrees C and 1 atm, Pd/C (A) was selective to phenol and cyclohexan-one/-ol and did not produce significant yields of benzene and cyclohexane, despite its high activity. Turnover frequencies for phenol (and cyclohexan-one/-ol) formation over the Pd/C catalysts were equivalent. Phenol, benzene and anisole were major products over Re/C after in situ reduction at 400 degrees C. The highest yield (52%) of fully deoxygenated products was obtained over PdRe/C after in situ reduction at 400 degrees C. We infer that the bimetallic catalyst combines synergistically the demethoxylation and hydrogenation functions of Pd/C with the capability of Re/C to deoxygenate phenol.