The solubility of hydrogen sulfide in 2 m (about 0.146 mass fraction) aqueous solutions of 1,4-diazacyclohexane (piperazine, PIPH(2)) was measured at low gas loadings (at stochiometric molar ratios of hydrogen sulfide to PIPH2 between about 0.14 and 1.04) and low partial pressures of hydrogen sulfide (from about (1.3 to 98.7) kPa) at (313.5 and 392.2) K by headspace gas chromatography. The new experimental results are a supplement to previously published data in the high gas-loading region. The new experimental data are compared to prediction results from a thermodynamic model that was based only on gas solubility data in the high gas-loading area. That thermodynamic model for describing the vapor-liquid equilibrium uses Pitzer's molality-based equation for the excess Gibbs energy of the aqueous solution. The average relative deviation between the new experimental results and the predictions for the partial pressure of hydrogen sulfide amounts to 10 %.