Knowledge of the chemical composition of wet air oxidation (WAO) effluents is essential in determining the effectiveness of the WAO system and in selecting further treatment. WAO with excess O 2 of cured green architectural polyester (33,77 g L -1 total solids) at 300 °C for 80 min gave 97% destruction of volatile solids, with 92% of the remaining total organic carbon (TOC) in the soluble form. Volatile fatty acids (C1-C5 with acetic acid as the major component) and other short organic acids (maleic and glyoxylic) and benzoic acid were also identified, in total comprising 98.5% of the soluble TOC. The polyester sample oxidized under O 2 limitation (107.01 g L -1 total solids) for 4 h at 290 °C showed 84% volatile solids destruction, with 67% of the remaining TOC in the soluble form, and gave a more complex range of organic compounds. Soluble effluent from both WAO processes showed good biodegradability both aerobically and anaerobically.