Highly porous cellular material (α-Al₂O₃-HPCM) support was synthesized by the template method. Highly porous support was used for the synthesis of the catalyst. A thin secondary layer with 25–30 μ thick γ-Al₂O₃ and zeolite Y was applied on the α-Al₂O₃-HPCM surface ((γ-Al₂O₃ (85%)-zeolite Y (15%))/α-Al₂O₃-HPCM). The catalyst based on the highly porous support was tested in a process of decreasing oil viscosity. The catalyst in the form of cylindrical granules and a thermal process of decreasing oil viscosity without the catalyst were used as the basis for comparison. α-Al₂O₃-HPCM in the catalyst provides low-quantity pores (d < 10 nm) and a quantity of general acid centers compared with the granular catalyst. On the other hand, it shows a more significant oil viscosity decrease (from 2500 to 41 cPs) and a low rate of gas generation (137 mL/h) for the catalyst with highly porous support. A high oil fraction was observed in the presence of the (γ-Al₂O₃-zeolite Y)/α-Al₂O₃-HPCM compared to the granular catalyst. The presence of large transport cells (pores) 1500–2000 μ for the catalyst based on highly porous support allowed a work period four times longer than that of experiment only with temperature without catalysts.