Direct photolysis (λ≥200nm) of acetophenone in aerated aqueous solution (10^-^4 mol.dm^-^3, pH=6) gave 2-hydroxyl and 3-hydroxyl acetophenone as the main intermediates. The photolysis was greatly depressed when the solution was degassed using N~2 during the irradiation. This suggests that the photodegradation proceeds via the attack of aromatic ring by reactive oxygen species which are formed from the reaction of dissolved oxygen with the excited organic substrate. It was also observed that the intermediates of hydroxyl acetophenone could undergo further photolysis to produce dihydroxyl acetophenone, and the first order apparent rate constant for the photo-disappearance follows the order: acetophenone>3-hydroxyl acetophenone>4-hydroxyl acetophenoned>2-hydroxyl acetophenone.

Key words: ACETOPHENONE, HYDROXY GROUP, DEGRADATION PRODUCTS, PHOTOLYSIS, LIGHT DEGRADATION, ORGANIC POLLUTANTS