New experimental results for the solubility of hydrogen sulfide in aqueous solutions of the single strong electrolytes sodium nitrate, ammonium nitrate, and sodium hydroxide at temperatures from 313 to 393 K and total pressures up to 10 MPa are reported. As in the strong electrolyte-free system, a second -hydrogen sulfide-rich - liquid phase is observed at high hydrogen sulfide concentrations. A thermodynamic model for describing the phase equilibrium is presented. Calculations are compared with the new experimental data.