We report measurements of the solubility of hydrogen in pure water and in sodium chloride brine of molality 2.5 mol/kg at temperatures between 323.15 K and 423.15 K and at pressures up to about 40 MPa. The estimated expanded relative uncertainty of the hydrogen solubility at given temperature and pressure is 3%, with a coverage factor of 2. The new results, together with data from the literature for hydrogen solubility in water and brine, are used to construct a simple model to predict hydrogen solubility in water and sodium chloride brines as a function of temperature, pressure and salt molality.