Catalytic activities of Al2O3-TiO2 supporting CoMo and NiMo sulfides (CoMoS and NiMoS) catalysts were examined in the transalkylation of isopropylbenzene and hydrogenation of naphthalene as well as the hydrodesulfurization (HDS) of model sulfur compounds, conventional gas oil (GO), and light cycle oil (LCO). Al2O3-TiO2 supporting catalysts exhibited higher activities for these reactions except for the HDS of the gas oil than a reference Al2O3 supporting catalyst, indicating the correlation of these activities. Generally, more content of TiO2 promoted the activities. inferior activity of the catalyst for HDS of the gas oil is ascribed to its inferior activity for HDS of dibenzothiophene (DBT) in gas oil as well as in model solvent decane, while the refractory 4,6-dimethyldibenzothiophene (4,6-DMDBT) in gas oil as well as in decane was more desulfurized on the catalyst. Characteristic features of Al2O3-TiO2 catalyst are discussed based on the paper results.