The electrochemical oxidation of olive mill wastewater (OMW) over a Ti/RuO2 anode was studied by means of cyclic voltammetry and bulk electrolysis and compared with previous results over a Ti/IrO2 anode. Experiments were conducted at 300-1,220 mg L-1 initial chemical oxygen demand (COD) concentrations, 0.05-1.35 V versus SHE and 1.39-1.48 V versus SHE potential windows, 15-50 mA cm(-2) current densities, 0-20 mM NaCl, Na2SO4, or FeCl3 concentrations, 80 degrees C temperature, and acidic conditions. Partial and total oxidation reactions occur with the overall rate being near first-order kinetics with respect to COD. Oxidation at 28 Ah L-1 and 50 mA cm(-2) leads to quite high color and phenols removal (86 and 84%, respectively), elimination of ecotoxicity, and a satisfactory COD and total organic carbon reduction (52 and 38%, respectively). Similar performance can be achieved at the same charge (28 Ah L-1) using lower current densities (15 mA cm(-2)) but in the presence of various salts. For example, COD removal is less than 7% at 28 Ah L-1 in a salt-free sample, while addition of 20 mM NaCl results in 54% COD reduction. Decolorization of OMW using Ti/RuO2 anode seems to be independent of the presence of salts in contrast with Ti/IrO2 where addition of NaCl has a beneficial effect on decolorization.