Four new Hofmann–3-phenylpropylamine (3PPA) type complexes with chemical formulae M(3PPA)2Ni(CN)4 (M=Ni, Co, Cd, and Pd) have been prepared and their vibrational spectra are reported in the region of 4000–60cm−1. The vibrational bands arising from 3PPA ligand molecule, the polymeric sheet and metal–ligand bands of the compounds are assigned. The thermal behaviour of these complexes is also provided using the DTA and TGA along with the magnetic susceptibility data. The results indicate that the monodentate 3PPA ligand molecule bonds to the metal atom of |M–Ni(CN)4|∞ polymeric layers and hence the compounds are similar in structure to Hofmann-type complexes.