Silica-alumina (SA)- and beta-zeolite (betaZ)-supported Pt, Pd, and Pt-Pd catalysts were compared for the simultaneous hydrogenation (HYD) of toluene (T) and naphthalene (NP) in the presence of dibenzothiophene (DBT). Under the selected conditions (P = 50 bar, T = 448 K, weight hourly space velocity (WHSV) = 25.8 h(-1)), all the catalysts were resistant to poisoning with 113 ppm of S (as DBT). The turnover frequency (TOF) calculated at zero time decreased in the following order: T > NP > DBT. On the basis of TOF values for the HYD of toluene, the monometallic Pt/betaZ showed larger activity than the bimetallic Pt-Pd-H/betaZ at short time on-stream, but this order was reversed under steady-state conditions. From FTIR of adsorbed CO and XPS measurements, the formation of the Pt-Pd alloy on this catalyst was excluded. The enhancement in activity observed for Pt-Pd-H/betaZ as compared with Pt/betaZ is related to the synergic effect of the two metals, which led to a lower deactivation and larger S-tolerance On the other hand, the high activity of the betaZ-as compared with SA-supported samples was attributed to the higher acidity of the former. The involvement of acid sites in activity was studied by comparing the performances of fresh and pyridine-neutralized Pt-Pd-H/betaZ and Pt/betaZ catalysts. For HYD of toluene, the value of TOFt=0 for the two zeolite catalysts was much lower on pyridine-neutralized samples, but still higher than on the non-neutralized Pt-Pd-L/SA and Pt-Pd-H/SA. It is proposed that Pt-Pd phases deposited on acidic betaZ develop stronger activity, which does not change after neutralization.