The relationship between the morphology and the selectivity of the sulfide phase in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and hydrodearomatization (HDA) reaction of 1-methylnaphthalene (1-MN) was studied. The morphology of the CoMo catalyst was tuned by increasing the metal content and adding organic compounds. The concentration of CoMoS sites at the corners (C(CoMoSc) and edges C(CoMoSE)) of the sulfide slabs were measured by X-ray photoelectron spectroscopy and high resolution transmission electron microscopytechniques. The corner and edge sites of the sulfide phase account for the direct desulfurization (DDS) and hydrogenation desulfurization (HYDS) routes in the HDS of 4,6-DMDBT, respectively. The hydrogen consumption analysis showed that the HYDS of 4,6-DMDBT and HDA of 1-MN both occur at the edge sites of the MoS2 slabs. The HYDS route in 4,6-DMDBT HDS was more promoted than the 1-MN HDA reaction when the stacking was increased. The turnover frequency of the corner sites for the DDS reaction and edge sites for the HYDS and HDA reactions were correlated with the length and stacking of the sulfide phase. The results revealed how the selectivities of the DDS, HYDS and HDA reactions as well as the hydrogen consumption can be tuned by modifying the morphology of the sulfide phase. (C) 2016 Elsevier B.V. All rights reserved.