Abstract: In a process for treating a gas containing hydrogen sulphide and sulphur dioxide, such as Claus plant tail gas, to substantially reduce emission of sulphur vapor in the treated gases, the process a characterized in that the gas is brought into contact with a solvent (5) in at least one gas-liquid reactor-contactor (2) and a gas (20) is recovered which is sent to a second reactor (102) where it is brought into contact with solvent (105), the solvent (105) being cooled by suitable means (190), to separate a portion of the sulphur from the solvent. The resultant solvent depleted in sulphur, contacts the gas (20) from the first reactor (2). The gas (120) from the second reactor is highly depleted in sulphur vapor. At least one of the reactors contains a catalyst. The solvent may be insoluble in water, e.g. dodecane, tridecane, naphtha, or soluble in water, e.g. glycerol, thiodiglycol, cyclohexanedimethylethanol, or an acid ester. The catalyst may comprise, e.g.