Figure shows the DFT calculated ∆H d of each composition in both the BCC and FCC lattices. Generally we observe that ∆H d of MgTiVNbZrHf > MgTiVNbCr > MgAlTiVCr. This is in good qualitative agreement with the ML model predictions and experimental PCT measurements of ∆H for MgTiVNbZrHf and MgAlTiVCr (57 and 44 kJ/molH 2 , respectively). Our DFT results also indicate that at higher hydrogen loading (e.g. H/M ≥ 1.2), the ∆H d of the FCC hydride is generally higher than that of the BCC hydride for all three compositions. This again is in good qualitative agreement with our experimental observation that the BCC alloy transforms into the FCC hydride upon hydrogenation for all three HEA compositions, i.e. the hydrogenation enthalpy is the driving force for the BCC→FCC structural transition.