Classic three phase catalytic-cocurrent downflow trickle bed reactor was compared, under the same operating conditions with a three phase cocurrent downflow vector named VERLIFIX. This reactor is an association of a Venturi device set above a fixed bed. The Venturi device allows a good gas-liquid mass transfer and an homogeneous distribution of the gas and liquid flows. The chemical reaction studied, in both reactors, is the catalytic oxidation of sulphur dioxide on active carbon particles. All experiments have been carried out at 25 degreesC. The presence of a Venturi distributor increases the gas-liquid mass transfer, the wetting efficiency of the catalyst and improve the conversion of sulphur dioxide. The Verlifix reactor is particularly adapted for heterogeneous reactions limited by gas-liquid and solid-liquid mass transfer.