The bromide minerals solubility in the mixed system (m(1)NaBr + m(2)MgBr(2))(aq) have been investigated at T = 323.15 K by the physico-chemical analysis method. The equilibrium crystallization of NaBr center dot 2H(2)O(cr), NaBr(cr), and MgBr2 center dot 6H(2)O(cr) has been established. The solubility-measurements results obtained have been combined with all other experimental equilibrium solubility data available in literature at T = (273.15 and 298.15) K to construct a chemical model that calculates (solid + liquid) equilibria in the mixed system (m(1)NaBr + m(2)MgBr(2))(aq). The solubility modeling approach based on fundamental Pitzer specific interaction equations is employed. The model gives a very good agreement with bromide salts equilibrium solubility data. Temperature extrapolation of the mixed system model provides reasonable mineral solubility at high temperature (up to 100 degrees C). This model expands the previously published temperature variable sodium-potassium-bromide and potassium-magnesium-bromide models by evaluating sodium-magnesium mixing parameters. The resulting model for quaternary system (Na + K + Mg + Br + H2O) is validated by comparing solubility predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solution models due to data insufficiencies at high temperature are discussed. (C) 2011 Elsevier Ltd. All rights reserved.