In the current study a series of pyrolysis and CO2 gasification experiments were conducted on a bed of kraft black char under a perpendicular impinging jet. The experiments demonstrated that the char bed carbon gasification rates are externally mass transfer limited. The mass transfer is further decreased by a net molar out-flow caused by the conversion of one mole of reactant CO2 to two moles of product CO via gasification. Predictions of the mass transfer coefficient using the COMSOL MultiPhysics finite element program were comparable with those obtained from the experimental data.