Density functional theory (DFT) and ab initio (Hartree-Fock) calculations employing the 6- 31G* basis set are used to determine gas-phase proton microaffinities ( PAn, i) of two bulky symmetrical tripodal tetraamine ligands N[(CH2) 4NH2] (3), trbn, and N[(CH2) 5NH2] (3), trpa. The corresponding proton macroaffinities ( PAn) are calculated not only according to our recently established method but also considering two alternative formulas based on a Boltzmann distribution. The successive protonation macroconstants in aqueous solution for these bulky amines are predicted from the well- defined correlation between the calculated proton macroaffinities, without considering Boltzmann distribution, and the corresponding log K-n for these amines. The overall protonation constants are also predicted by two different methods.