The chemical composition of organic matters (OMs) in domestic wastewater was determined in order to investigate types and origin of OMs, which will supply a more scientific basis for COD fractions of activated sludge models (ASMs) and wastewater treatment management. Chemical hydrolysis and chromatographic analysis were used to quantify macromolecular OMs such as proteins and sugars. Results suggested that the largest group of OMs in the domestic wastewater was fibers. Proteins and sugars were the next two largest groups in the wastewater. Fibers, proteins and sugars accounted for 20.64%, 12.38% and 10.65% of TOC in the wastewater, respectively. Ten endocrine disrupting chemicals were determined in the wastewater; most of them were PAHs and phthalates. The sum of volatile fatty acids, soluble proteins and soluble sugars formed about 30% of total COD of the wastewater, and not all the soluble proteins and sugars were degradable substrates. The largest part of TOC in the wastewater was supra colloidal. Most proteins and sugars in the wastewater were larger than 0.001 mu m. 0 2010 Elsevier B.V. All rights reserved.