The separation of bulk quantities of H2S from CO2 was investigated through a series of pressure-swing adsorption experiments utilizing 4A, 5A, and 13X molecular sieves. High selectivity of H2S over CO2 was encountered for all sieves, particularly for the 13X and 5A. Practically pure CO2 was produced in the adsorption stage with fresh 5A and 13X sieves, at high product recovery rates. Efficient H2S purification was obtained with fresh 5A and regenerated 4A zeolites. The experimental results were in line with theoretical predictions of the literature.