A small batch reactor is developed to study the removal of phenol from a thin layer of water by creating pulsed corona discharges above the water. Pulses of up to 40 kV are applied with a duration of similar to 50 ns and an energy of similar to 60 mJ. In this CAW (Corona Above Water) reactor an ozone yield of upto 90 g/kWh is obtained in ambient air. The phenol degradation is 48 g/kWh, using a 1 mM initial concentration in demineralized water. The degradation yield increases to almost 100 g/kWh by adding to the water either H2O2 or Fe2SO4 or NaOH. The first two additions are considered to increase to amount of OH radicals. In the case of NaOH addition it is observed that much more ozone dissolves in the water. The addition of the OH scavenger t-butanol shows that in most cases the main oxidation route of phenol in the CAW reactor is direct ozone attack.