We report enthalpies of formation from the elements and oxides, Delta H-f degrees = -(22,673.44 +/- 30.19) kJ(-1) mol(-1) and Delta H-f,H-ox = -(869.68 +/- 28.75) kJ . mol(-1), for [GeO4Al12(OH)(24)(H2O)(12)](SeO4) (4)center dot 12H(2)O((cr)) (GeAl12) measured using high temperature oxide-melt solution calorimetry. This material is the selenate salt of the germanium-substituted polynuclear Al-13(7+) ion in the e-Keggin structure. We also report heat capacities from temperatures of (2 to 300) K on this GeAl12 selenate and its other heterometal substituted forms, Na[AlO4Al12(OH)(24)(H2O)(12)](SeO4)(4)center dot 12H(2)O((cr)) (AlAl12) and Na[GaO4Al12(OH)(24)(H2O)(12)](SeO4)(4)center dot 12H(2)O((cr)) (GaAl12), measured using a Quantum Design Physical Property Measurement System (PPMS). These measurements were used to calculate entropies and subsequently free energies of formation for these three materials. All three MAl12 selenates, where M = Al(III), Ga(III), or Ge(IV), have similar heat capacities from temperatures (2 to 300) K and similar characteristic Debye temperatures, Theta(D), suggesting similar lattice vibrational densities of states. (C) 2015 Elsevier Ltd. All rights reserved.