Dilute solutions of lead ranging from 10(-5) to 10(-9) M were investigated using a rather simple carbon paste electrode with a conducting binder. Typically made of 200 mg of high-purity graphite powder and 200 mm(3) of 1 M HClO4 the paste was used without any other additive. After the electrode cavity had been filled with ca. 4 mg of paste, a preconcentration step on open circuit was performed, with stirring, in the test solution of lead. The response of electrode was related to the concentration of lead, the time of preconcentration and the nature of the binder. 1 M HClO4 appeared to be suitable for lead analysis even when cadmium or copper were present. An ion exchange between protons of the binder and lead in the bulk was found.