A method is presented for trace-element analysis of lead and zinc by potentiometric stripping analysis (PSA) where both the glassy-carbon working electrode and the electrolyte are free of mercury. Analysis of zinc requires an activation of the glassy-carbon electrode. The activation is performed by pre-concentrating zinc on glassy carbon at −1400 mV(SCE) in a mercury-free electrolyte containing 0.1 M HCl and 2 ppm Zn2+, followed by stripping at approx. −1050 mV. A linear relationship between stripping peak areas, recorded in the derivative mode, and concentration was found in the range 0–2000 ppb.