a b s t r a c tTiAlZr mixed oxides, synthesized using sol-gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H 3 PMo 12 O 40 or its cobalt salt Co 1.5 PMo 12 O 40 . Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS).No formation of a new oxide phase was revealed in the synthesized mixed materials. However the effect of separated oxides on the structure of ternary oxides was observed. Maximum in HDS activity of Mo containing samples was determined by optimum content of alumina in the mixed oxides. Incorporation of cobalt into the heteropolyacid increased the HDS activity about two times and masked the effect of the support composition.