Performance of a 3-dimensinal electrolytic process used for the treatment of dilute solutions wasinvestigated in two different oxidation modes, i. e. direct oxidation on the surface of electrode and indirect oxidationthrough the formation of oxidant. Decolorization of indigotrisulfonate in these oxidation was measured and represented as an equivalent oxidation performance by O₃. Experimental results demonstrated that electric current efficiency in the direct oxidation was 96% and energy consumption was significantly smaller than that of commercially-available ozonizer. However, the indirect oxidation process has poor performance in terms of electric current efficiency (1%) and energy consumption.It was considered that the direct oxidation process would be a feasible alternative of conventional oxidation process in water and wastewater treatment.