The advanced chemical oxidation of raw and biologically pretreated textile wastewater by (1) ozonation, (2) H2O2/UV-C oxidation and (3) sequential application of ozonation followed by H2O2/UV-C oxidation was investigated at the natural pH values (8 and 11) of the textile effluents for 1 h. Analysis of the reduction in the pollution load was followed by total environmental parameters such as TOC, GOD, UV-VIS absorption kinetics and the biodegradability factor, f(B). The successive treatment combination, where a preliminary ozonation step was carried out prior to H2O2/UV-C oxidation without changing the total treatment time, enhanced the COD and TOC removal efficiency of the H2O2/UV-C oxidation by a factor of 13 and 4, respectively, for the raw wastewater. In the case of biotreated textile effluent, a preliminary ozonation step increased COD removal of the H2O2/UV-C treatment system from 15% to 62%, and TOC removal from 0% to 34%. However, the sequential process did not appear to be more effective than applying a single ozonation step in terms of TOC abatement rates. Enhancement of the biodegradability factor (fB) was more pronounced for the biologically pretreated wastewater with an almost two-fold increase for the optimized Advanced Oxidation Technologies (AOTs). For H2O2/UV-C oxidation of raw textile wastewater, apparent zero order COD removal rate constants (k(app)), and the second order OH. formation rates (r(i)) have been calculated. (C) 2001 Society of Chemical Industry.