The solubility of hydrogen sulfide in aqueous solutions of N-methyldiethanolamine (MDEA) and MDEA sulfate (2 and 1 m, respectively) and in aqueous solutions of MDEA and sodium sulfate (2 and 1 m, respectively) was measured at temperatures from 313 to 393 K and total pressures up to about 3.9 MPa. The experimental results are used to extend and test a model for the thermodynamic equilibrium encountered in the solubility of hydrogen sulfide in such aqueous solutions.