NiCoMo/Al₂O₃ catalysts were prepared with Co₂Mo₁₀-heteropolyacid and Co(Ni) citrate.

Adding the Co(Ni) to Co₂Mo₁₀/Al₂O₃ altered the active phase structure and morphology.

Activity in DBT HDS passed through maximum at 0.33 of the molar ratio Co(Ni)/(Co + Ni + Mo).

NiCoMo/Al₂O₃ catalysts indicated higher rate constants in DBT HDS than CoMo/Al₂O₃.

NiCoMo/Al₂O₃ catalyst with minimal Ni/Mo ratio had NiMoS sites with the highest TOF number.