The results of the theoretical study of NH4+(H-2)(n), (n = 1-8) clusters are presented. Two shells for ligand binding which are characterized by the vertex or face binding of H-2 to the NH4+ tetrahedron were determined. The main difference in the nature of interactions observed in the structurally different complexes comes from the electrostatic interactions. The dispersion energies are found to be less dependent on the geometry of the complex or on the charge of the core. The properties investigated such as dissociation energy and enthalpy, electronic density distribution and stretching vibrations of H-2 are similar for molecules occupying the same shell and are significantly different when neighboring shells are compared.