By employing a specific particle interaction theory and a high-precision equation of states for the liquid and vapor phases of H₂, respectively, a new H₂ solubility model in pure water and aqueous NaCl solutions is proposed in this study. The model established by fitting the experimental data of H₂ solubility can be used to estimate H₂ solubility in pure water at temperatures and pressures of 273.15–423.15 K and 0–1100 bar, respectively, and in salt solutions (NaCl concentration = 0–5 mol/kg) at temperatures and pressures of 273.15–373.15 K and 0–230 bar, respectively. By adopting the theory of liquid electrolyte solutions, the model can also be used to predict H₂ solubility in seawater without fitting the experimental data of a seawater system. Within or close to experimental data uncertainty, the mean absolute percentage error between the model-predicted and experimentally obtained H₂ solubilities was less than 1.14%.