A study on the hydrotreating performance of sulfided NiMo supported in NH4+Y- and H+Y-modified Al2O3 is reported. The effect of the addition of the corresponding NiMo-exchanged zeolites was also investigated. The materials were characterized (by N-2 physisorption and surface acidity measurements) and evaluated in the upgrading of a middle. distillates (LCO-SRGO) mixture under industrial conditions. The main effects of the integration of the NiMo-exchanged zeolite (from the NH4+-faujasite) were an improvement of textural properties and the creation of strong surface Lewis sites. The corresponding sylfided formulations showed higher hydrodesulfurization and hydroclearomatization activities than the catalyst prepared from the protonic zeolite.