A process for preparing a slurry catalyst composition suitable for the hydroconversion of heavy oils comprising: (a) mixing a Group VI B metal oxide and aqueous ammonia to form a Group VI metal compound aqueous mixture; (b) sulfiding, in a first reaction zone the aqueous mixture of step (a) with a gas comprising hydrogen sulfide to a dosage greater than 8 SCF of hydrogen sulfide per pound of Group VIB metal (4.7 x 10 -4 Nm 3 /g) to form a slurry; (c) promoting the slurry with a Group VIII metal; (d) in a mixing zone mixing the slurry of step (c) with a first hydrocarbon oil under an inert atmosphere and in a high shear mode in the range from 100 RPM to 1600 RPM, the first hydrocarbon oil having a viscosity of from 2 cSt @ 212°F (2 mm 2.s -1 @ 100°C) to 15 cSt @ 212°F (15 mm 2.s -1 @ 100°C), to form Mixture X; (e) moving and combining Mixture X with hydrogen gas and a second hydrocarbon oil in a second reaction zone and mixing in a high shear mode in the range from 100 RPM to 1600 RPM, the second hydrocarbon oil having a boiling point in the range from 50°F (10°C) to 300°F (148.9°C) and having a lower viscosity than the first hydrocarbon oil, thereby forming an active catalyst composition admixed with the first hydrocarbon oil and the second hydrocarbon oil; and (f) recovering the active catalyst composition by separation from the second hydrocarbon oil; wherein the conditions in the first reaction zone comprise a temperature in the range from at least 80°F (26.7°C) to 200°F (93.3°C), and a gauge pressure in the range from at least 100 psi to 3000 psi (0.69 - 20.7 Mpa); and wherein the conditions of the second reaction zone comprise a temperature in the range from at least 350°F (176.7°C) to 600°F (315.6°C), and a gauge pressure in the range from at least 1000 psi to 3500 psi (6.89 - 24.1 MPa); and wherein the ratio of the volume of the second oil to the first oil is greater than 1. (a) mixing a Group VI B metal oxide and aqueous ammonia to form a Group VI metal compound aqueous mixture; (b) sulfiding, in a first reaction zone the aqueous mixture of step (a) with a gas comprising hydrogen sulfide to a dosage greater than 8 SCF of hydrogen sulfide per pound of Group VIB metal (4.7 x 10 -4 Nm 3 /g) to form a slurry; (c) promoting the slurry with a Group VIII metal; (d) in a mixing zone mixing the slurry of step (c) with a first hydrocarbon oil under an inert atmosphere and in a high shear mode in the range from 100 RPM to 1600 RPM, the first hydrocarbon oil having a viscosity of from 2 cSt @ 212°F (2 mm 2.s -1 @ 100°C) to 15 cSt @ 212°F (15 mm 2.s -1 @ 100°C), to form Mixture X; (e) moving and combining Mixture X with hydrogen gas and a second hydrocarbon oil in a second reaction zone and mixing in a high shear mode in the range from 100 RPM to 1600 RPM, the second hydrocarbon oil having a boiling point in the range from 50°F (10°C) to 300°F (148.9°C) and having a lower viscosity than the first hydrocarbon oil, thereby forming an active catalyst composition admixed with the first hydrocarbon oil and the second hydrocarbon oil; and (f) recovering the active catalyst composition by separation from the second hydrocarbon oil; wherein the conditions in the first reaction zone comprise a temperature in the range from at least 80°F (26.7°C) to 200°F (93.3°C), and a gauge pressure in the range from at least 100 psi to 3000 psi (0.69 - 20.7 Mpa); and wherein the conditions of the second reaction zone comprise a temperature in the range from at least 350°F (176.7°C) to 600°F (315.6°C), and a gauge pressure in the range from at least 1000 psi to 3500 psi (6.89 - 24.1 MPa); and wherein the ratio of the volume of the second oil to the first oil is greater than 1.