In this work, we determined thermodynamic properties of a suite of tin perovskites □₂(BSn⁴⁺)(OH,O)₆ that correspond to the minerals burtite (B = Ca), jeanbandyite (Fe³⁺), schoenfliesite (Mg), wickmanite (Mn), vismirnovite (Zn), and mushistonite (Cu). Purity of the samples was verified by powder X-ray diffraction, chemical analysis (ICP-OES), solid state ¹¹⁹Sn magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, ⁵⁷Fe Mössbauer spectroscopy, thermogravimetry (TG), and Karl-Fischer titration. Enthalpies of formation (Δ_fH^o) were determined by acid-solution calorimetry (in 5 N HCl at T = 298 K, with SnCl₄ as the reference phase), that for jeanbandyite also in high-temperature oxide-melt calorimetry (in sodium molybdate at T = 973 K, with SnO₂ as the reference phase). For the two methods, the difference for the Δ_fH^o values is 10.7 kJ·mol⁻¹, a fair agreement. Because of the high H₂O content of the studied phases, acid-solution calorimetry was given preference as it is less sensitive to errors in H₂O determination. Entropy was estimated, including configurational or magnetic contribution. The resulting Δ_fG^o (kJ·mol⁻¹) and logK_sp values are: CaSn(OH)₆ −1885.8±7.6, 7.7; FeSn(OH)₅O −1425.4±7.6, −5.8; MgSn(OH)₆ −1812.4±7.5, 3.3; ZnSn(OH)₆ −1519.6±7.6, 0.7; MnSn(OH)₆ −1598.7±7.7, 1.0; CuSn(OH)₆ −1311.2±7.9, 0.0. The logK_sp value relate to reaction MSn(OH)₆ + 6H⁺→ M²⁺ + Sn⁴⁺ + 6H₂O or FeSn(OH)₅O + 7H⁺→ Fe³⁺ + Sn⁴⁺ + 6H₂O. The solid solution between vismirnovite and mushistonite was found to be thermodynamically non-ideal, with a mixing parameters W=−15.38 kJ·mol⁻¹. Calculations of Gibbs free energies of selected reactions show that the tin perovskites are stabilized at basic pH. For example, burtite becomes stable with respect to cassiterite (SnO₂) in systems buffered by calcite, gypsum or the C-S-H phase from cement at pH > 9–10.5. Similarly, jeanbandyite is stabilized in systems buffered by ferrihydrite [Fe(OH)₃] but not in those buffered by goethite (FeOOH). Saturation indices calculated from polluted water in field settings show the same trend; the tin perovskites are stable under alkaline conditions and the solutions become supersaturated with respect to the tin perovskites. Hence, under alkaline conditions, such phases could take up and retain tin in the environment.