New Hofmann-type tetracyanoaqua 2-methylpyrazine metal (II) nickelate (II) benzene clathrates, [M(H2O)(2 mpz)Ni(CN)4] C6H6 (where 2 mpz = 2-methylpyrazine (C5H6N2); M=Mn(II) or Cd(II); C6H6=benzene) have been prepared in powder form and characterized by infrared and Raman spectroscopy. Thermal behaviors of these compounds are followed using thermo-gravimetric analysis and differential thermal analysis (DTA) techniques. The spectral features suggest that these compounds are similar in structure to the Hofmann-type two-dimensional coordination polymer compounds. The metal (II) ions are coordinated by aqua, 2-methylpyrazine ligands, and four N atoms of CN groups in the tetracyanonickelate ions. A detailed analysis of the vibrational spectra indicates the presence of hydrogen bonding between the ligand molecules of the host lattices and p electrons of the benzene molecule. The spectral data show that the positions of almost all bands due to the guest molecule remain practically unchanged on enclathration. The C, H, N, and metal analyses were carried out for all the compounds and were found to fit the proposed formulas well. The experimental results are in agreement with the proposed formulas. © Taylor & Francis Group, LLC.