The presence of solvent molecules, even inert, may significantly influence processes taking place in the gas phase. The reason for the solvent activity may be found in studies of complexes originating from microsolvation. The structure, thermodynamics, and vibrational properties of NH4+ Ar-n ( n = 0-5) and NH3Arn ( n = 0-4) complexes are presented in this work with the aim to elucidate the effect of microsolvation on protonation/deprotonation processes. The relation between the nature of interactions in cationic and neutral clusters and the proton affinity is studied as a function of the number of ligands in complexes.