The ligand potassium hydrotris(N- (2,6-xylyl)-2-thioimidazolyl)borate (KTtxylyl) was utilized to construct a carbon paste modified electrode (KTtxylyl/CPE), which was studied using electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry (SWV). Its electrochemical response was investigated, and it demonstrated a significant improvement in the detection of both lead(II) and cadmium(II), allowing determination of lead(II) at trace concentrations. The spectroscopic evidence includes FT-IR, Raman, 1H NMR and also DFT calculations using B3LYP/LANL2DZ level of theory indicate the high affinities of these ions toward the ligand forming lead(II) and cadmium complexes of the type [TtxylylMCl]. Negative electrostatic potential of the tri(thione) donors deriving their binding abilities toward both ions. The detection limits based on 3(SD/m) were; 0.112 μM and 0.204 μM for lead(II) and cadmium(II), respectively. The simultaneous detection of these ions in several waste water samples was examined in order to verify the modified electrode. Data from the ICP-AES instrument was compared to the results obtained.