Abstract: Dairy industry is one of the largest food processing industry which causes severe environmental problems due to the generation of wastewater containing high Solid concentration, high BOD and COD. The removal of COD plays a vital role in the treatment design. An attempt has been made to remove COD from dairy wastewater using water hyacinth - low cost biosorbent as a cleaner production option. The wastewater was collected from AAVIN dairy, Coimbatore and analysed for various physic-chemical parameters. The COD value was found to be 2850 mg/l. Batch study was adopted in this investigation and COD reduction was determined. The optimum contact time was found to be 40 minutes for a COD reduction of 65.4% and optimum dosage was observed as 15 g with an removal efficiency of 89.5%.