Oil field produced water by separated with crude oil were treated by an electrochemical process in laboratory pilot-scale plant, using double anodes with active metal (M) and graphite (C) and iron as cathode and a noble metal content catalyst with big surface. Due to the strong oxidizing potential of the chemicals produced (Cl-2, O-2, OCl-, HO center dot and so on), when the wastewater pass through the laboratory pilot-scale plant the organic pollutants including bacteria were oxidized and coagulated by produced Mn+ ion. It can be concluded that the catalytic electrochemical treatment of oil field produced wastewater is effective. Both chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were reduced by over 90% in 6 min, suspense solids (SS) by 99%, Ca2+ content by 22%, corrosion rate by 98% and bacteria (sulphate reducing bacteria (SRB), saprophyfic bacteria (TGB) and iron bacteria) by 99% in 3 min under 15 V/120 A. These results indicate that this catalytic electrochemical method could be used for effective oil field wastewater treatment for injection purpose. (c) 2005 Elsevier B.V. All rights reserved.