In a process for removing hydrogen sulfide from an oxygen- containing gas stream by passing the gas stream through caustic- impreganted activated carbon, the stream containing from about 5 ppm to about 10,000 ppm by volume of hydrogen sulfide, improvement in which the breakthrough capacity of the caustic-impregnated activated carbon for hydrogen sulfide is extended by the addition of ammonia to the air stream at or about the time that the aforementioned breakthrough capacity has been reached or exceeded, the amount of added ammonia being such that its concentration is at least equal to the concentration of hydrogen sulfide but preferably not greater than about 50 ppm by volume.
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