Investigation of the degradation of cresols in the treatments with ozone

► Reaction of O3 with three cresol isomers used as model compounds for humic material. ► Ozone reacts preferentially with the aromatic ring, not the methyl group. ► Highly hydrophilic reaction by-products are formed from cresols after ring-opening. ► Chloroformate derivatives of degradation intermediates are identified by GC-ECNI-MS.