The design and operation of such processes can be optimized via models that can accurately simulate the partitioning of these gases between an aqueous and gaseous phase. Our results show that the models implemented in PHREEQC and Reaktoro predict very well the solubility of individual gases such as CH4, N2, CO2, H2S, O2, and H2 in water at a high range of temperature and pressure conditions with both phreeqc and pitzer databases. Yet, for higher ionic strength systems, where non-idealities prevail, the performance of the models is heavily impacted by the selected thermodynamic database. While "phreeqc.dat" reflects correctly the decreasing CH4, N2, H2, and O2 solubility in electrolyte solutions of increasing ionic strength (Figures , 67, and 77, respectively), "pitzer.dat" does not account for the effect of salinity on the solubility of these individual gases. The opposite is observed for the CO2 and H2S gas systems (Figures and, respectively), whose solubility in brines is more accurately described by the pitzer database compared to phreeqc.dat. The default pitzer database distributed with PHREEQC contains interaction parameters between H2S with Cl -, Na + , and SO 4 -2 and between CO2 with HSO 4 -, SO 4 -2 , Na + , Mg +2 , and K + , which eventually improves its performance compared to phreeqc.dat for CO2 and H2S systems. These interactions are not defined for the other gases tested in this work. This pitfall can be handled by editing the database and defining interaction parameters between the different gases and ionic species as previously suggested in .