Degradation of dye Maxilon Yellow GL (MY GL) (Basic Yellow 45) was investigated with anaerobic mixed culture using glucose (3000 mg 1(-1) COD) as carbon source and electron donor throughout batch experiments. Zero-, first- and second-order reaction kinetics were used to find out the suitable substrate removal and decolorization kinetics. The substrate removal (COD) process is suitable for second-order reaction kinetics among the kinetic models studied. Decolorization process also approximates to second-order kinetics between 50 and 1000 mg 1(-1) of MY GL concentration. Substrate and color removal rates (mg 1(-1) h(-1)) were found to be 6.38, 5.98, 4.6, 4.16, 3.64, 2.86, 2.34 and 0.075, 0.0149, 0.0265, 0.0303, 0.0426, 0.053, respectively, in all serum bottles throughout the incubation period. Color removal efficiencies decreased as the influent dye concentration increased. The highest removal efficiency (80%) was obtained with 50 and 100 mg 1(-1) of MY GL dye concentrations. However, the lowest removal efficiency (28%) was found with a 1000 mg 1(-1) of MY GL dye concentration. Complete dye reduction was not found for this basic dye. The results indicate that anaerobic mixed culture can decolorize low concentration of this basic dye. (c) 2006 Elsevier Ltd. All rights reserved.