The FCC dynamics has been studied to determine the effect of operating conditions on multiplicity of steady states. The proposed model is capable to analyze several dynamic features to characterize the FCC process. Three combustion modes are analyzed: Partial combustion, total combustion and transition mode. At least three steady states have been determined in both partial and complete combustion modes. Furthermore, it is established in this paper that operating conditions are incapable to change the number of steady states. It is believed that a similar analysis should be applied to identify the effect on the multiplicity of physical parameters such as oxidation rates. (C) 2005 Elsevier Ltd. All rights reserved.