Selective ring opening (SRO) is an attractive route for promoting cetane index of LCO feeds in order to get high quality diesel fuel. High performing noble metal based catalysts have been proposed for this purpose; however, considering the possibility of performing SRO in the hydrotreating units, thio-resistant catalysts for SRO would be more adapted. In the present study, we investigated the performance in decalin conversion of bifunctional NiW sulfide catalysts deposited on silica alumina. Impact of acidity by modulating Si/Al content or promoting by P or F was studied, as well as the improvement of the hydrogenation/hydrogenolysis function by the use of chelating agents (citric acid). The analytical investigation performed in this work relied on comprehensive two-dimensional GC-MS. A 3D view of a typical GCxGC chromatogram obtained from the analysis of liquid samples collected is shown in Figure 1. A careful separation of obtained product families disclosed important information on hydrogenolysis or hydrogenation characters of catalytic sites in the complex reaction network involved.