Electro-coagulation of a blue reactive dye (Drimarene K2LR CDG Blue) solution has been optimised by experimental design and surface response analysis in terms of colour removal and chemical oxygen demand (COD) decrease. The optimal conditions (pH, current density, reaction time) have then been applied to other reactive dyes solutions as well as synthetic and real textile wastewater samples. The biodegradability before and after electro-coagulation has been assessed by short-term respirometry and is increased by this type of treatment. (C) 2004 Elsevier B.V. All rights reserved.