Tri-iodide charge-transfer complexes synthesized upon the chemical interaction between iodine and tryptophan or tyrosine were characterized using different spectroscopic techniques (e.g., infrared, Raman, electronic, X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The triiodide charge-transfer complexes were prepared by dry grinding of potassium iodide, iodine and amino acid with 1:1:1 molar ratio in presence of few drops of absorption bands around 360 and 280 nm due to the formation of the triiodide ion (I 3  ). The Raman spectra show the characteristic bands for the triiodide ion at 160, 126 and 100 cm -1 , which are assigned to  as (I-I),  s (I-I) and  (I 3  ), respectively. The iodine complexes were shown to contain the triiodide species based on the electronic absorptions as well as on the Raman absorption bands characteristic for the non-linear triiodide species, I 3  , with C symmetry. The proposed structures of these complexes are further supported by thermal analyses measurements. The DC electrical properties as a function of temperature of these charge transfer complexes have been studied.