The investigations of acid-base properties of the several small molecules by quantum chemical methodsThe values of ionization potentials calculated for several hydrides and fluorides were obtained by UHF 3-21, UHF 3-21+G and UHF 3-21++G ab initio methods. Quantum chemical calculations show that protonation reactions of the four-atomic hydrides of nitrogen subgroup elements give cations with tetrahedron geometry. Protonation reaction of molecules of the boron subgroup elements follow form with undefined structure.