Sulphur dioxide absorption rate in sulphuric acid solutions and activated carbon slurries was studied in a flat interface stirred cell. Experiments were performed in which the stirrer speed, the weight fraction of catalyst, the particle size and the partial pressures of both SO2 and O-2 were varied. The gas-liquid mass transfer rate was found to be enhanced by the presence of powder activated carbon in the liquid film close to the interface. As the heterogeneous oxidation rate of sulphur dioxide was slow compared to the adsorption rate, and the activated carbon used had a very high adsorption capacity, the enhancement was probably due to both the shuttle effect and the adhesion of the powdered catalyst to the gas-liquid interface.