BACKGROUND: Electrochemical advanced oxidation treatment using boron-doped diamond (BDD) electrodes is a promising technology to treat small amounts of toxic and biorefractory pollutants in water. This process has been tested on the degradation of naproxen, a common pollutant drug present in surface waters. To optimize the process a series of experiments have been designed to study the interaction between four variables: pH (over the range 5-11); current (0-320 mA cm(-2)); supporting Na2SO4 electrolyte concentration (0-0.375 mol L-1); and solution flow rate (Q(v)) between 3.64 and 10.8 cm(3) min(-1). RESULTS: Among these variables the influence of current was the greatest, the second was the salt concentration, the third flow rate, and the fourth pH. An ANOVA test reported significance for seven of the fourteen variables involved and the degradation of naproxen was optimized using response surface methodology. CONCLUSIONS: Optimum conditions for naproxen removal (100%) were found to be pH = 10.70, Q(v) = 4.10 cm(3) min(-1), current density = 194 mA cm(-2) using a supporting electrolyte concentration of 0.392 mol L-1. (C) 2010 Society of Chemical Industry