The pure zeolite-like galloborate of the K-2[Ga(B5O10)]center dot 4H(2)O sample has been synthesized by a mild hydrothermal method and characterized by means of chemical analysis, XRD, FT-IR, and DTA-TG techniques. The molar enthalpies of solution of KGa(SO4)(2)center dot 12H(2)O(s) in the mixture of 1 mol.kg(-1) HCl and calculated amount of K2B4O7 center dot 4H(2)O, of K2SO4(s) in the mixture of 1 mol.kg(-1) HCl and calculated amount of H3BO3, of K-2[Ga(B5O10)]center dot 4H(2)O(s) in the mixture of 1 mol.kg(-1) HCl and calculated amount of K2SO4 and H3BO3 at 298.15 K were measured, respectively. With the incorporation of the previously determined enthalpies of solution of H3BO3(s) and K2B4O7 center dot 4H(2)O(s) in 1 mol.kg(-1) HCl, together with the use of the standard molar enthalpies of formation for K2B4O7 center dot 4H(2)O(s), KGa(SO4)(2)center dot 12H(2)O(s), K2SO4(s), H3BO3(s), and H2O(l), the standard molar enthalpy of formation of -(5768.5 +/- 9.1) kJ.mol(-1) for K-2[Ga(B5O10)]center dot 4H(2)O(s) was obtained on the basis of the appropriate thermochemical cycle. In addition, the standard molar enthalpy of formation of -(5757.6 +/- 0.8) kJ.mol(-1) for KGa(SO4)(2)center dot 12H(2)O(s) was also obtained according to its molar enthalpy of solution of (45.15 +/- 0.11) kJ.mol(-1) in H2O at 298.15 K.