The present work reports the effect of CO2 concentration and system pressure on radiation heat transfer in a pressurized circulating fluidized combustor. The basic heat transfer mechanism in a pressurized circulating fluidized bed combustor is presented. For a given CO2 concentration in a pressurized circulating fluidized bed combustor, radiation heat transfer increases slightly with system pressure due to increased gas partial pressure and gas emissivity. The results demonstrate that for the given CO2 concentration, the effect of system pressure on radiation heat transfer is minimal in a pressurized circulating fluidized bed (PCFB) combustor. The effect of variation in CO2 concentration lever oft bed to wall radiation heat transfer during combustion in a pressurized circulating fluidized combustor is not significant for a narrow combuster.