The use of a tubular electrochemical reactor (TER) with a novel design for batch recycle electrochemical treatment of petroleum refinery effluent was investigated. The reactor is composed from a cylindrical stainless steel cathode and a spiral porous graphite anode at its center. The impact of process factors like: NaCl addition ,current density, flow rate, and pH on the chemical oxygen demand elimination efficiency was studied using response surface methodology based on (BBD). For estimating the interaction between the response (RE %) and its independent factors, a quadratic model equation was developed. The quadratic model's accuracy was supported by its significant R2 value (92.61 %). The optimization study illustrated that NaCl addition was the most effective factor on RE% followed by current density confirming that the oxidation process is governed by indirect electrochemical oxidation rout. Results also showed that the flow rate plays an important influence in maximizing the RE% with a new correlation. The optimal working conditions were a current density ( 26 A/cm2), pH (10), NaCl addition ( 1.899 g/l) and flow rate ( 4L/min), resulting in a (COD ) elimination efficiency of 85.12% with specific energy exhaustion of 116.17kWh/kg COD.