The anodic oxidation of phenol using porous graphite was investigated in this study. The experiments were designed so that the effect of residence time at different currents on phenol oxidation would be elucidated. Phenol removal efficiency was a function of the applied current and the residence time and was around 50% at a current of 2.0 A and a residence time of 35 min. Phenol removal efficiency was found to increase with the increase in current and residence time. An empirical model was developed to predict the effect of flow rate or residence time and current on the phenol removal efficiency. Percentage of phenol completely oxidized, measured by the amount of CO2 produced, increased with current and residence time and reached 48% at a current of 2 A and a residence time of 23.3 min. It was found that the phenol removal rate increases with the decrease in residence time. Maximum current (CO2) efficiencies were achieved at currents of 1.0 and 1.25 A at residence times of 35 and 23.3 min, respectively. Residence time was identified as an important parameter in affecting removal efficiency and complete detoxification of phenol.