BACKGROUND: Metoprolol is a beta-blocker that can be found in urban wastewaters and which is not removed efficiently by conventional wastewater treatments. In this work, the removal of this pollutant by conductive diamond electrochemical oxidation (CDEO) is studied. RESULTS: CDEO is able to degrade Metoprolol tartrate down to the 10 ppb level ( detection limit of the technique used) with a current charge requirement that increases with increase in the initial concentration of pollutant, although it is many times greater than the stoichiometric current charge required. CDEO also removed very efficiently the reaction intermediates. In terms of TOC the depletion follows a first-order kinetic, but the kinetic constant of Metoprolol decreases with concentration. NaCl increases significantly Metoprolol degradation rate, but it barely affects the TOC removal rate. CONCLUSIONS: CDEO can be used to remove Metoprolol from wastewaters, independently of the initial concentration of compound. Several reaction intermediates are formed during the electrolyses although their concentrations are very low and negligible compared with that of Metoprolol. The removal rate ( in terms of TOC) does not depend on the nature of the electrolyte used. The process is under mass transfer control for the complete range of concentrations studied. (C) 2011 Society of Chemical Industry