Model Predictive Control has been used for control of the fluidized catalytic cracking process. The constrained optimization problem involved in the control has generally been solved in a piece-meal fashion in practice. For improved control, the optimization problem needs to be solved directly, that is, without decomposition. In a previous paper, the results of a direct solution using an LP formulation were presented on a simple mathematical model of the FCC process. In this paper, the results of the direct solution are presented on a comprehensive mathematical model of the FCC process. The results show that improved control performance can be obtained by including the constraints within the optimization problem.