Electrochemical phenol degradation using a platinum-coated Ti electrode was comparatively investigated at different pH levels, which were maintained over the entire operation period. Various analyses such as phenol concentration, TOC, COD, cyclic voltammetry, and total current efficiency were conducted to determine the performance of phenol degradation in the presence of Na2SO4 as the electrolyte. The phenol and COD removal rate were relatively higher at lower pH conditions (pH 3 and 5) due to high oxidant generation of OH radical and H2O2. At pH 5 condition, phenol (90 mg L-1) was completely removed after a 24-h operation. However, complete COD removal was obtained after about 250-h operation, due to byproduct formations (hydroquinone and polymers) during the phenol degradation. Cyclic voltammetry analysis indicated that acidic conditions could inhibit the oxygen-evolution reaction, causing an increase in current efficiency and a decrease in energy consumption. This study suggests that phenol-contaminated wastewater can be efficiently treated by an electrochemical process using a Pt/Ti electrode with continuously controlled lower pH conditions.Phenol oxidation by electrochemical treatment system at different pH conditions Electrochemical reactor (inside) R: reference electrode, A: Pt/Ti anode, C: Ti cathode, G: pipe to the gas bag, S: sample holder, M: magnetic stirrer.