Heat capacities of Sr-, Rb-, and Cs-hollandite with the compositions Ba1.14Sr0.10Al2.38Ti5.59O16, Ba1.17Rb0.19Al2.46Ti5.53O16, and Ba1.18Cs0.21Al2.44Ti5.53O16 were measured from T = (2 to 300) K using a Quantum Design Physical Property Measurement System (PPMS). From the heat capacity results, the following thermodynamic parameters have been determined. The characteristic Debye temperatures Theta(D) over the temperature range (30 to 300) K of Sr-, Rb-, and Cs-hollandite are T = (1782, 189.7, and 189.2) K, respectively, and their standard entropies at T = 298.15 K are (413.9 +/- 8.3), (415.1 +/- 8.3), and (419.6 +/- 8.4) J . K-1 . mol(-1). Combined with previously reported formation enthalpies, their corresponding Gibbs energies of formation from oxides (Delta(f)G(ox)degrees) are (-194.9 +/- 11.4), (-195.0 +/- 12.8), and (-201.1 +/- 12.8) kJ . mol(-1), and those from elements (Delta(f)G(el)degrees) are (-7694.6 +/- 12.5), (-7697.0 +/- 13.9), and (-7697.1 +/- 13.9) kJ . mol(-1) at T = 298.15 K. The similarities among the obtained Delta(f)G(ox)degrees values suggest that the three substituted hollandites have similar thermodynamic stabilities at standard conditions, which is in agreement with the ease of Cs-Rb-Sr substitutions in the hollandite structure. (C) 2015 Elsevier Ltd. All rights reserved.