The solubility of sulfur in hydrogen sulfide has been determined by an absolute method at 21 combinations of pressure and temperature within the range of 1,020 to 4,520 psia and 110 deg. to 230 deg. F. respectively. Results, which appear to be consistent within about 2 percent, show the solubility to increase with pressure along an isotherm but to pass through maxima along isobars. Where direct comparison can be made, our values differ drastically from published results at lower pressures and are in serious disagreement at higher pressures. The solubility of sulfur in carbon disulfide is reported for pressures from 1,020 to 5,020 psia at 150 deg. F. No published data were found for direct comparison. Both the solubility of sulfur and the density of saturated solutions decrease with increasing pressure at this temperature. Introduction: Difficulties in production arise when a fluid containing a high content of hydrogen sulfide occurs in a reservoir in which elemental sulfur is present Changes in pressure and temperature present Changes in pressure and temperature can cause deposition of dissolved sulfur from hydrogen sulfide-rich fluids in both the formation and the production tubing. The first step in a study of this problem is to determine the solubility of sulfur in pure hydrogen sulfide under conditions of interest in production. This report presents results of one such study. Values published in the literature generally appear to be grossly in error. In some approaches to repairing the damage caused by sulfur plugging of formation and tubing, carbon disulfide is used as a solvent. Experiments were run at a typical temperature of 150 deg. F and elevated pressure to obtain basic data on the solubility of sulfur in carbon disulfide.