The determination of hydrogen sulfide in effluents from coal-fired furnaces and incinerators is complicated by the presence of sulfur oxides (which form acids). Organic compounds also may interfere with or prevent the formation of the cadmium sulfide precipitate or give false positive results because of reaction with iodine. The report presents a technique in which these effects are overcome by collecting the gases in a strongly basic medium and separating the cadmium sulfide by filtration. Subsequent analysis is performed by visual comparison or iodometrically depending on the quantity of cadmium sulfide present. (Author/RH)