This project was initiated by the API CREC Committee in order to provide a computer program for sour water stripper design calculations based on an evaluation.of new and existing vapor-liquid behavior of ammonia - hydrogen sulfide - water mixtures. The scope of this project was subsequently expanded by the author with approval from the CREC Committee to include carbon dioxide as a fourth component. This change was recommended because of new measurements sponsored by the API Technical Data Committee at the Thermochemical Institute on ammonia - carbon dioxide - hydrogen sulfide - water mixtures.