Hydrogen is the only gas able to dissolve in aluminum. The solubility S of hydrogen in Al obeys the Sieverts' law and S is much larger in the liquid phase (above 660.4 degrees C) than in the solid one. This might lead to the formation of porosity during aluminum casting. In the present work, the ternary system Al-H-RE (RE = Er, La, Y) is investigated. The equilibria between the different phases are determined.in the presence of liquid Al, RE and H2 gas by both experimental measurements and phase diagram calculations. The possible formation of metallic hydrides and the change in the hydrogen solubility S are discussed regarding pressure and temperature determining the thermodynamics of the system. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.