Lead is one of the toxic heavy metal when presented in a high level over it allowable limit. To detoxify this heavy metal a chelators were used as in a chelation therapy. This work studies the complexation of some chelators (penicillamine and quercetin) with Pb II ion. A spectrophotometric techniques were applied in water and water-ethanol mixture as a solvent, at four different temperature. A shift in it ï¬max and decrease in absorbance indicating the complex formation. The stoichiometry of these complexes were determined by a method of the continuous variation (JobÂs) method, it was found that Pb-quercetin (1:1), and Pb-penicillamine (2:1). These chelatorÂs have a high tendency to complex with Pb II ion which were reflected by its high values of their equilibrium constants. Thermodynamic parameters indicate a spontaneous interaction (negative free energy change ïGo), and the enthalpy changer have negative ïHo which depends on type of the interaction and the structures of the complexes. The kinetic calculations shows a second order interaction.