Voltammetric techniques were used for the simultaneous determination of copper, cadmium and soluble lead in lead-acid battery electrolyte without any manipulation of the sample, thus allowing the sample to be returned to the battery if required. The proposed method consists in transferring 10 ml of 38% H₂SO₄ directly into the voltammetric cell and, after de-aeration, the solution was subjected to differential-pulse anodic stripping voltammetry for the determination of cadmium and soluble lead and to differential-pulse polarography for the determination of copper. The responses were at –0.600, –0.435 and –0.005 V versus an Ag-AgCl reference electrode for cadmium, lead and copper, respectively. The responses were proportional to the respective metal concentrations from at least 0.03 to more than 1–5 µg ml^–1 in 38% H₂SO₄, with a relative standard deviation of 2–3% at 0.06 µg ml^–1. The results were checked by cold vapour atomic absorption spectrometry. The effect of other ions on the proposed method was also evaluated.