Ultraviolet spectrophotometric investigation were carried out on the systems of pyridine, ${eta}$-picoline and 3,5-lutidine with iodine in carbon tetrachloride. The results reveal the formation of one to one molecular complexes of the type, $C_5H_5N{cdot}I_2$, ${eta}-C_5H_4(CH_3)N{cdot}I_2$ and 3,5-$C_5H_3(CH_3)_2N{cdot}I_2$. The equrilibrium constants of complexes were obtained in consideration of that absorption maxima have the blue shift with the increasing temperatures according to the formation of the charge transfer complexes. The thermodynamic parameters, ${Delta}H$, ${Delta}G$ and ${Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicated that the relative stabilities of the pyridine, ${eta}$-picoline and 3,5-lutidine complexes with iodine increase in the order, pyridine < ${eta}$-picoline < 3,5-lutidine. These results were supposed to be the influence resulted from increase of electron density by the positive inductive effect and the dipole moment of the steric hindrance effect. And this results were compared and discussed with polymethylbenzene-iodine CT-complexes.