Some new platinum (IV) and palladium (II) thiodiamine complexes of type [Pt(L) 2 Cl 2 ] and [Pd(L)Cl 2 ], [where, L=(cyclohexyl-N-thio)-1,2-ethylenediamine (L 1 ) and (cyclohexyl-N-thio)-1,3-propanediamine (L 2 )] have been synthesized. The thiodiamines coordinate as a bidentate N–S ligand. The synthesized platinum (IV) and palladium (II) complexes of the thiodiamines were characterized by elemental analysis, IR, mass, electronic and 1 H NMR spectroscopic studies. These complexes were also screened for cytotoxicity, in vitro antifungal and in vitro antibacterial activities. Thermodynamic parameters such as activation energy (E a ), apparent activation entropy (S # ) and enthalpy change (ΔH) for the dehydration and decomposition reactions of one complex has also been evaluated.