Solid state characterization of poly(L-lysine)hydrobromide was obtained via differential scanning calorimetry, thermogravimetric analysis, optical microscopy and infrared spectroscopy. The glass transition temperature of poly(L-lysine) hydrobromide is 178 degrees C. This thermal transition has not been reported previously. Poly(L-lysine)＇s T-g decreases when complexes are produced with the following divalent transition metal chlorides; cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride dihydrate and anhydrous zinc chloride. At 10 mol% salt, nickel chloride decreases T-g by 45 degrees C, and the general trend is Ni2+>Co2+>Zn2+>Cu2+. The depression of poly(L-lysine)＇s T-g correlates well with ligand field stabilization energies for pseudo-octahedral and pseudo-tetrahedral d(n) complexes (n = 7, 8, 10) from the 1(st) row of the d-block. However, d(9) copper(II) complexes cannot be included in this empirical correlation. Infrared spectroscopic evidence suggests that Co2+, Ni2+ and Zn2+ coordinate to the carbonyl oxygen in the main chain of the polymer. When transition metal ions coordinate to C=O, the network of hydrogen bonded amide groups is disrupted, which lowers the glass transition. The amide I region of the infrared spectrum reveals a hydrogen bonded C=O stretch @ 1655 cm(-1) that is characteristic of poly(alpha-amino acid) random coil conformations, and a metal-ligand coordinated C=O stretch @ 1625 cm(-1) in complexes with divalent cobalt, nickel and zinc. The amide II region of the infrared spectrum near 1550 cm(-1) is also sensitive to the formation of coordination complexes with these d-block metal chlorides.