Zirconium-doped mesoporous silica with a Si/Zr molar ratio of 5 has been used as a support for bimetallic Ru-Pd catalysts. The effect of palladium as a promoter in a catalyst containing ruthenium as active phase, and the influence of the Ru/Pd atomic ratio were studied in the hydrogenation and ring-opening reaction of tetralin. The results indicate the promotional effect of Pd on hydrotreating activity of catalyst since an increase is observed in the formation of hydrogenation products, especially trans-decalin at low temperatures for 5-RuPd(8/1) and 5-RuPd(4/1), while at higher temperatures, there is an enhacement in the production of hydrogenolysis/hydrocracking products. In contrast 5-RuPd(15/1) catalyst shows at low temperatures lower yields of hydrogenation products and higher yields of high molecular weight products (HMW) than 5-Ru catalyst while at higher temperatures than 315 degrees C only produces HMW products. The best catalytic performance is displayed by the 5-RuPd(8/1) catalyst, giving a conversion of tetralin of 98.5% as well as high yields of hydrogenation (20.8%) and ring-opening (70.1%) products under the following experimental conditions: temperature of reaction 350 degrees C; H-2/tetralin molar ratio of 10; contact time 2.8 s and total pressure of 6 MPa (P(H-2) = 4.5 MPa and P(N-2) = 1.5 MPa). Moreover, this catalyst exhibits good thiotolerance in the presence of 600 ppm of dibenzothiophene in the feed, and an excellent tolerance to nitrogen compounds even with 2000 ppm of acridine. (c) 2006 Elsevier B.V. All rights reserved.