Abstract: A process is provided for the removal of hydrogen sulfide out of a gas stream by contacting the hydrogen sulfide contaminated gas with a solution of chelated metal catalyst, such as iron EDTA, in a scrubbing vessel so as to result in a cleaned gas and a scrubbing solution containing elemental sulfur and a reduced chelated metal catalyst. A portion of the hydrogen sulfide contaminated feed gas is branched off from the rest of the hydrogen sulfide contaminated feed gas, at a location upstream of the scrubbing vessel, and injected into a bisulfide generating vessel where it is contacted with an aqueous caustic solution, such as an aqueous solution of potassium hydroxide, wherein the hydrogen sulfide reacts with the caustic solution to result in a cleaned gas and a solution containing bisulfide ions.