Immobilized cell utilization in tower type bioreactor is being studied extensively as a promising alternative for industrial bioprocess. In the cephalosporin C production process, a strictly aerobic fungus is utilized and intraparticle oxygen transfer can limit the production. To study quantitatively this limitation, results from free cells bioprocess and immobilized cells in Calcium alginate gel bends process were compared through a mathematical model. The free cells process showed higher production rate while the immobilized cells process achieved higher specific production rate in relation to sucrose consumption. Furthermore,the model of the heterogeneous reaction system considering intraparticle diffusion limitation explained fairly well the behavior of the process.