Chemical Looping Combustion (CLC) is comprised of two reactors, in which direct contact between air and fuel is avoided. A metal oxide, as oxygen carrier, transports oxygen from the air reactor to the fuel reactor while circulating between them. Based on the hydrodynamics coupled with reaction kinetics of oxygen carrier from the literature, a model for an interconnected fluidized bed reactor has been developed to optimize the design and operation of the reactor system. The model considers the chemical reaction of a single particle and a particle population balance for the calculation of bed particle conversion. The core-annulus and two-phase hydrodynamic models are assumed for the air and fuel reactors, respectively. Predictions of the oxygen emission, particle conversion and fuel conversion efficiency under different operating conditions are presented for a pilot scale CLC reactor system