International audience; NH4-dawsonite is a promising alternative precursor for the preparation of alumina catalyst supports. Since generally prepared by precipitation, a good knowledge of its thermodynamic properties and its solubility would allow a better control over its synthesis. However, only few research efforts have focused on this material aspect until now. We propose in this study to estimate the order of magnitude of the NH4-dawsonite Gibbs free energy at 25 °C by combining experimental solubility measurements and theoretical solubility calculations. The latter were performed within the pH range 3-14 and considering the predominant Al species Al 3+ , Al(OH) 3 0 and Al(OH) 4-. The NH4-dawsonite Gibbs free energy obtained with this method was-1564 ± 2 kJ.mol-1 .