a one dimensional dynamic model for a riser reactor in a fluidized bed catalytic cracking unit (fccu) for gasoil feed has been developed in two distinct conditions, one for industrial fccu and another for fccu using various frequencies of microwave energy spaced at the height of the riser reactor (fccu-mw). in addition, in order to increase the accuracy of component and bulk diffusion, instantaneous and overall fractional yield is used in a heuristic manner. furthermore, the effect of various catalysts to oil ratio on gasoline yield with fccu-mw has been studied. the results of the convectional fccu simulation show great compatibility with the plant data in hand. comparison of the two models shows that microwave energy gives better results in terms of gasoline yield. also it has been shown that the increase of catalyst to oil ratio leads to the increase of gas oil conversion and especially gasoline yield. keywords: modeling – simulation - fluidized bed catalytic cracking – microwave energy – riser reactor the work done in this study is organized into six chapters. the first chapter represents introduction of the fluid catalytic cracking unit (fccu). a literature review on the modeling and simulation of fccu follows in the second chapter which consists of kinetic development, modeling and simulation review and fcc evolution. chapter 3 deals with the riser model development. in this section energy balance, partial and overall mass balance equations have been derived. also, energy balance for a model of a fccu riser reactor exposed to microwave energy (fccu-mw) is given. experimental relationship is used to model the pressure behavior in the riser section of fccu. instantaneous and overall fractional yield is used to increase the accuracy of component and bulk diffusion in a heuristic manner. chapter 4 represents simulation steps of riser reactor of a fcc and fcc-mw models. results of the riser simulation in both fccu and fccu-mw are presented and discussed in chapter 5. simulation results are compared with industrial data and other simulations that have been reported in the literatures. after that results of the models that simulated in the present work are compared. chapter 6 summarizes the conclusions drawn from the study. also a new fccu using microwave energy is recommended which has been registered as a patent in the iranian patent organization.