Abstract A technique for the determination of labile Pb in sea-water has been developed which uses co-deposition with mercury on 6–14-mg pyrolytic graphite platforms, followed by electrothermal atomization of the deposit. Optimization of the applied voltage, pH and sodium chloride concentration with respect to the deposition efficiency yielded a detection limit of 0.15 μg/l. Pb for 120-sec depositions with a single platform. As the amount of deposit increases linearly with deposition time up to 5 min and the simultaneous use of two platforms increases the analytical signal by a factor of 1.73, a further improvement is possible. Near-shore sea-water and estuarine water samples containing lead in the concentration range 0.4–1.3 μg/l. were analysed with an RSD better than 10%. Background correction was not required as the technique eliminates spectral interferences due to molecular absorption.