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Molybdenum (at 2.8, 3.3, 4.0 and 4.7 atoms nm⁻²) and cobalt (Co/(Co + Mo) ratios of 0.3, 0.4 and 0.5) were impregnated on wide-pore ZrO₂–TiO₂ mixed oxides (30–70) prepared with solvo-thermal treatment (80 °C, 1 day). Materials characterization comprised N₂ physisorption, XRD, thermal analyses, and UV–vis DRS, Raman, and IR spectroscopies. For impregnated dried materials (non-calcined) at concentrations beyond 3.3 atom nm⁻² and activated by sulfiding (H₂S/H₂, 400 °C) no further improvement in activity in dibenzothiophene (DBT) hydrodesulfurization (HDS) (at 5.59 MPa, T = 320 °C) was observed. Thus, monolayer Mo dispersion was assumed at that content. The aforementioned formulation was chosen to be promoted by Co at different concentrations, the maximum HDS activity being found for sulfided catalyst with Co/(Co + Mo) = 0.4. Nevertheless, the promotion observed by Co addition was small …