Mixed sulfided CoMo catalysts supported on γ-Al2O3 and halloysite nanotubes (HNTs) were synthesized by incipient wetness impregnation with salt solutions of Keggin-type phosphorus- and vanadium-containing heteropolyacids. The synthesized materials were characterized by low-temperature nitrogen adsorption, energy dispersive X-ray fluorescence analysis, temperature-programmed reduction (both for the oxide and sulfide catalysts), and Raman spectroscopy, and were tested in hydrogenation of naphthalene and hydrodesulfurization of dibenzothiophene. The HNT-supported catalyst exhibited a greater activity in these reactions.