An anaerobic packed column reactor was operated continuously at different dyestuff loading rates, (0.05-0.4 g/(1 day)) and COD loading rates (1-8 g/(1 day)) in order to determine dyestuff and COD removal kinetic constants. The system was operated at room temperature (20 +/- 1 degrees C) and at pH 7 using an immobilized anaerobic bacterial consortium called PDW. Synthetic wastewater containing textile dyestuff Reactive Red 195 was fed from the bottom of the reactor. Around 90% decolourization efficiency was obtained for dyestuff loading rates up to 0.15 g/(1 day). COD removal efficiency was obtained between 5 and 35% for the applied loads. Modified Stover-Kincannon model was applied to the experimental data. Saturation value constant and maximum utilization rate constant of Stover-Kincannon model for dyestuff and COD were determined as K-B = 17.8 g/(1 day), U-max = 19.5 g/(1 day) and K-B = 37.9 g COD/(1 day), U-max = 12.9 g COD/(1 day), respectively. The predicted effluent dyestuff and COD concentrations were calculated using the constants and it was found that they are in good agreement with the observed ones. (c) 2004 Elsevier Ltd. All rights reserved.