Preparation of the o-diphenylphosphinobenzaldehyde complexes of Pd(II) and Pt(II), with general formulae [MX2L2], [Pd2Me2(mu-Cl)(2)L-2] and [PdMeClL2] where [M = Pd or Pt; X = Cl, Br, I and L = o-diphenylphosphinobenzaldehyde, {PPh2(o-C6H4CHO)}], is reported here. All complexes have been characterized by elemental analysis, IR, NMR (H-1, C-13, P-31 and Pt-195) and UV-visible spectroscopy, that allowed the deduction-of the stereochemistry for the complexes. The mononuclear complexes have been found to adopt the trans configuration in square-planar geometries. The molecular structure of trans-[PdCl2{PPh2(C6H4CHO)}(2)] has been established by a single crystal X-ray diffraction study and confirms the spectroscopic conclusions.