The simplified Clegg-Pitzer equations are used to correlate the solubility data for CO2 and H2S over a wide range of solvent concentrations (12-50 wt % methyldiethanolamine (MDEA) aqueous solutions), temperature (25-120 degrees C), partial pressure of acid gases (0.001-5290 kPa), and acid gas loading (0.001-1.0 mol/mol) from different authors. The interaction parameters thus obtained can be used to predict the solubility data for the mixed acid gases in CO2-H2S-MDEA-H2O systems without any additional adjustable parameters.