For this present work, a series of Au-metallized TiO2 catalysts were synthesized and characterized in order to compare their performance in two different catalytic environments: the phenol degradation that occurs during the liquid phase and in the CO oxidation phase, which proceeds the gas phase. The obtained materials were analyzed by different techniques such as XRF, SBET, XRD, TEM, XPS, and UV-Vis DRS. Although the metallization was not totally efficient in all cases, the amount of noble metal loaded depended strongly on the deposition time. Furthermore, the differences in the amount of loaded gold were important factors influencing the physicochemical properties of the catalysts, and consequently, their performances in the studied reactors. The addition of gold represented a considerable increase in the phenol conversion when compared with that of the TiO2, despite the small amount of noble metal loaded. However, this was not the case in the CO oxidation reaction. Beyond the differences in the phase where the reaction occurred, the loss of catalytic activity during the CO oxidation reaction was directly related to the sintering of the gold nanoparticles.