Reverse pulse amperometry is introduced as an electroanalytical technique which, when applied with a mercury electrode, is capable of monitoring fluid streams for the presence of electroactive metal ions without the requirement of deaeration. The technique is based on the application of an unsymmetrical square wave with a large negative initial potential for reduction of the metal ion followed by a positive potential pulse for oxidation of the reduction product. The analytical signal is measured only during the stripping process at a potential where dissolved oxygen is not reduced. A variety of metal ions were found to be detectable by RPA;An approximate mathematical derivation is presented to describe the response of RPA;RPA was applied with a thin-film mercury electrode (TFME), hanging mercury-drop electrode (HMDE) and "static" dropping mercury electrode (SDME) and the response of these electrodes was compared;RPA was applied with a HMDE and cation-exchange liquid chromatography to determine Pb in a standard reference material from the National Bureau of Standards (NBS SRM 1571, orchard leaves).