A previously developed model describing bubbling fluidized bed reactors is used in this investigation to study the effect of various important hydrodynamic, operating and design parameters on the performance of a large scale fluidized bed reactor used in oxidative coupling of methane. Three kinetic schemes obtained from the literature have been used in this study. The model predicted fairly well the Experimental results reported recently under different reaction conditions. The simulation results revealed that increasing the ratio of methane to oxygen in the feed leads to lower methane conversion hut higher Ct selectivity. As the ratio is decreased the system loses its fixed-point stability to a periodic stability. Higher methane conversion and product selectivity are obtained upon decreasing the feed how rate and particle diameter. (C) 2001 Elsevier Science B.V. All rights reserved.