Two new mercury(II) Schiff base complexes [Hg((2,6-Cl-ba)2-1,2-pn)X2] (X = Cl (1), I (2) and (2,6-Cl-ba)2-1,2-pn = N,N'-bis(2,6-dichlorobenzylidene)-1,2-diaminopropane) have been synthesized and characterized by elemental analysis (CHN), FT-IR and 1H-NMR spectroscopy. The crystal structure of complexes 1 and 2 were determined by single-crystal X-ray diffraction. X-ray results shown that the mercury(II) ions in these complexes have a distorted tetrahedral geometry with HgN2Cl2 and HgN2I2 chromophores, respectively. In these complexes, the Schiff base ligand (2,6-Cl-ba)2-1,2-pn act as chelating bidentate ligand, coordinating via the two iminic nitrogen atoms and it adopts an E,E conformation. Finally, the thermal behavior of complexes was study using thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathway.