In this study, coagulation-flocculation processes are used to decolourize and biodegradate textile finishing industry effluents. The optimum coagulant dose and pH value are determined by comparing the effectiveness of alum, FeSO4 and FeCl3 for obtaining maximum colour and COD removals. Coagulant doses varied from 500 mg/l to 2000 mg/l at two pH values of 9.0 and 9.5 for FeSO4, 6.0 and 6.5 for alum and FeCl3. The initial colour and total COD of wastewater were measured to be 3670 Pt-Co and 1015 mg/l, respectively. Varying the FeSO4 dose from 500 mg/l to 2000 mg/l at pH 6.0, colour and COD removals increased from 18% to 89% and 60% to 74%, respectively. A 48% COD removal was obtained using 500 mg/l alum at pH 6.0. Increasing the alum dose up to 2000 mg/l shifted COD removal up to 65%, whereas 61%-72% COD removals were obtained varying FeCl3 dosage from 500 mg/l to 2000 mg/l at this pH. Since both alum and FeCl3 did not provide more than 35% colour removal, FeSO4 was chosen as optimum coagulant. No effluent toxicity under these optimum conditions was measured using 24-h newborn daphnids.