Cutting oils are emulsionable fluids widely used in metal and mechanical working processes, as coolant, lubricants and metal forming fluids, which contains mineral oils, water and additives (fatty acids, surfactants, biocides etc). This paper investigates the demulsification of soluble oil-water emulsion by electro-oxidation (EO) using a Ti/RuO2 in batch and continuous mode, is optimized by using response surface methodology (RSM). It examines the effect of pH, current, flow-rate and electrolysis time on the removal efficiencies of demulsification process. Removal efficiencies are studied in terms of % oil removal, % turbidity removal and % COD removal for batch and continuous mode. The optimum pH, current and electrolysis time were found to be 7.23, 0.50 A, and 99 min and elapsed time, flow-rate and current was 170 min, 2.2 cc/min and 1.11 A for batch and continuous process respectively. The pH was most significant parameter it gives higher removal efficiencies at neutral pH. The EO performance for continuous process was found to be affected by the flow rate and elapsed time. The results demonstrated that both batch and continuous processes were effective to treatment of soluble cutting oil emulsion. (c) 2017 The Electrochemical Society. All rights reserved.