PURPOSE: To improve and maximize the utilization of hydrocarbon feedstock.

CONSTITUTION: A method for maximizing the utilization of hydrocarbon feedstock comprises steps: to fractionate a cat cracker effluent into a reduced emission gasoline blending stream, a heavy cat naphtha stream and a light cat cycle oil stream; to feed the heavy cat naphtha stream and optionally a part of the light cat cycle oil to a selective membrane extraction unit wherein a saturates-rich retentate and arom. compds., polar- and heteroatom-rich permeate are produced; to produce high quality jet fuel or distillate by hydrotreating the retentate; and to produce hydrocrackate and gas by hydrocracking the arom. compd. rich permeate.