Electro-oxidation (EO) is one of the most promising forefront technologies to remove pollutants from wastewater. Most of the available references have shown interesting results for biorefractory compounds, especially at laboratory scale. However, the continuous operation of an EO process has not been studied in detail, even less at pilot scale. In this work, the EO technology has been applied to treat an effluent from an Urban Waste Water Treatment plant in a pilot scale with an anodic area of 0.35 m(2) (boron-doped diamond electrodes) taking into account the previous results obtained at lab scale (electrode area 7 x 10(-3) m(2)). A model based on the mass balance, leads to the Damkohler number as the main parameter to describe the removal of organic matter expressed as chemical oxygen demand (COD) at lab pilot scales. COD reduction is possible to manage by adjusting the flow rate to the anodic area ratio. The main difficulties for the process at pilot scale came from the formation of nonconductive films, which increases near two times the energy losses.