A three-dimensional and two-phase flow model to predict the dynamic behavior of a fluid catalytic cracking (FCC) industrial reactor was developed in this work. The study took into account heat transfer and chemical reactions. A four-lump model was proposed to represent the catalytic cracking reactions in which the heavy oil (gas oil) is converted into gasoline and light hydrocarbon gases. Gas acceleration inside the reactor due to molar expansion and a model to describe undesirable catalyst deactivation by coke deposition on its surface were also considered. An Eulerian description of the phases was used to represent the two-phase flow. A commercial CFD code (Ansys CFX version 11.0) was used to obtain the numerical data. Appropriate functions were implemented inside the CFX code to model the heterogeneous kinetics and catalyst deactivation. Results show nonuniform tendencies inside the reactor, emphasizing the importance of using three-dimensional models in FCC process predictions. (C) 2011 Elsevier Ltd. All rights reserved.