Over the course of the commercial fluid catalytic cracking (FCC), catalyst deactivation occurs both reversibly, as a result of side reactions that eventually yields coke, and irreversibly, due to contaminants present in the feedstock or to the dealumination of the zeolite catalyst component. Herein, we discuss the deactivation of HY zeolite and FCC catalysts from a fundamental as well as an applied point of view. Aspects related to the various causes of FCC catalysts (and additives) deactivation under industrial conditions are also summarized. (C) 2008 Elsevier B.V. All rights reserved.