A catalytic method for treating an H2S/SO2 mixture for producing liquid sulphur including the following steps: a) at least one step of heating the mixture containing H2S/SO2 to a temperature Tc; b) at least one step of catalytically reacting the heated mixture obtained in a) in the presence of at least one catalyst and at least one step of recovering the exiting mixture containing gaseous sulphur; and c) at least one step of converting the gaseous sulphur contained in the exiting mixture obtained at step b) into liquid sulphur, wherein between step b) and step c), the temperature Ts of said exiting mixture and the dew point Tr of the gaseous sulphur contained in said exiting mixture are measured and in that the heating temperature Tc of step a) is adjusted so that the temperature Ts is 5° C. to 30° C. above the dew point Tr.