[en] The IR spectra of tetra-2,3-pyridinoporphyrazine (H₂L) and its metal complexes (ML) in the solid phase have been obtained and analyzed. The interaction of solid layers of H₂L and ML with gaseous HCl and DCl, which results in the formation of the protonated species H₃LH_n⁺ and MLH_n⁺ and their deuterated analogs, has been investigated spectroscopically. It has been shown that the reaction takes place in two steps, which presumably differ with respect to the number of protons added. The conclusion that the protons are preferentially localized on the nitrogen atoms of the pyridine rings has been confirmed