In this work, the electrocoagulation technique was studied in order to treat chemically stabilized concentrated oil-water emulsions. This study was mainly focused on the effects of operating parameters on the reduction rate of chemical oxygen demand (COD): initial pH, current density, reaction time, electrode distance and inlet concentration. The removal curves showed that the electrocoagulation process exhibits three phases: (1) an initial phase, (2) a reactive phase and (3) a steady-state phase. The results showed that the period to reach the reactive phase decreased as the current density increased and the pH values decreased. It is suggested that the main destabilization mechanism is the sweep coagulation and the bridging flocculation through the aluminum hydroxide precipitates and the polymeric cations hydroxoaluminum respectively, which are the predominant species in the pH range 5 - 9,5. Finally it was observed, that inlet oil concentration and distance between electrodes did not present any significant effect on the treatment efficiency but the last could reduce significantly the power consumption, for the conditions taken in this work.