Electrolysis of an aqueous solution at subcritical water conditions, referred here as wet electrolytic oxidation (WEO), results in a completely different reaction product compared to that from usual water electrolysis. Oxygen, hydrogen and chlorine evolution is almost completely suppressed when carrying out the electrolysis of aqueous NaCl solution at temperatures higher than 250 degrees C. Chemical oxygen demand (COD) compounds can be completely mineralized by this electrolytic reaction, but this work focused in partial oxidation of organic sludge and combining with biological process. The treatment of organic sludge by WEO increased the biodegradability of organic sludge due to the formation of organic acids. The electrochemical reaction of WEO suppressed the evolution of color that often appears in subcritical water treatment of organic waste. (C) 2007 Elsevier B.V. All rights reserved.