Abstract: The invention relates to a process for catalytic cracking and the associated apparatus in which the cracking reaction takes place in two substantially vertical and successive reaction zones, the loads being introduced into the first zone where it circulates from the top downwards, then at least a part of the product obtained is introduced into a second reaction zone in which it circulates in an ascending fashion. A supplementary hydrocarbonated phase is advantageously introduced into the product entering the second zone. The invention applies particularly to heavy loads, with a U-shaped apparatus.