Wastewater characterization is an integral part of treatment and management strategies for industrial effluents. This paper outlines the results of detailed characterization studies on three different tannery complexes. It evaluates, aside from raw wastewater quality in terms of major polluting parameters, the impact of physical and chemical settling on wastewater characteristics. Emphasis is placed upon homogenization and sulfide removal potential. Chemically treated wastewater is further studied for assessing COD fractionation, presently used as significant modelling information for biological treatability. (C) 1997 IAWQ. Published by Elsevier Science Ltd.