A distortion of the aromatic character as a result of the N_py protonation of 2-aminopyridine was established by conventional and linear-polarized IR-spectroscopy, UV- and ¹H-NMR-spectral analysis of model system 2-aminopyridinium tetrachlorocuprate (II) salt. Quantum chemical ab initio calculations are performed at MP2 and B3LYP levels of theory and 6-311 ++G** basis set in order to determine the changes in the geometrical parameters and IR-spectroscopic characteristics as a result of N_py protonation. The observed crystallochromy effect is discussed as well.