The infrared spectra of a number of square planar palladium (II) complexes of the type M 2PdX 4, PdL 4X 2, and trans and cis isomers of PdL 2X 2 (where M = NH 4 +, K +, Rb +, or Cs +; L = NH 3; X = Cl −, Br −, or I −) have been recorded from 4000 to 40 cm −1. The compounds were examined both at room temperature and at liquid nitrogen temperature. The investigation of four tetrachloropalladium (II) complexes gave Pdz.snfc; stretching vibrations in the range 327–336 cm −1, Pdz.snfc; in-plane bending vibrations in the range 183–205, and Pdz.snfc; out-of-plane bending vibrations from 160 to 175 cm −1. Four similar bromo complexes gave the corresponding PdBr vibrations in the ranges 249–260 cm −1, 130–169 cm −1 and 114–140 cm −1, respectively. The PdN in and out-of-plane bending vibrations of the tetraamine complexes were found in the ranges 245–273 and 160–190 cm −1, respectively. By using the assignments for the tetrahalo and tetraammine complexes as well as isotopic shift data, assignments for the fundamental modes for a series of cis and trans dihalodiammine complexes of palladium (II) are given and discussed.