FIELD: petroleum processing. SUBSTANCE: in the first step, heavy oil fractions come into contact with catalyst containing on amorphous carrier at least one IV group element and at least one VIII group element at temperature 350-430 C, pressure 5-20 MPa, space velocity 0.1-5.0 hr-1, and hydrogen-to- hydrocarbons volume ratio 150 to 2000. First step product is then brought into contact with catalyst containing on carrier at least one VI group element, at least one VIII group element, and zeolite Y at temperature 350-430 C, pressure 5-20 MPa, and space velocity 0.1-5.0 hr-1. Resulting product is fractionated into middle distillates and residue containing base oils. EFFECT: widened base oil range and improved quality of middle distillates. 17 cl, 2 tbl, 5 ex
