Hydrocracking is a catalytic cracking process involving hydrogen that facilitates virtually complete conversion of the feedstock. The objective is to break down the large molecules of the wax distillate into smaller molecules. To do this, gas oil is mixed with hydrogen, heated and conveyed through a reactor with a fixed bed catalyst. The hydrocarbons then pass into a separator, where excess hydrogen is separated and returned to the cycle. Finally, the gases are separated. This process continues until the feedstock is completely converted. A high pressure and a high level of hydrogen consumption (sometimes in the form of a suitable production plant) are necessary for this process.