The ability of the white rot fungus Coriolus versicolor, to produce enzymes during its growth and decolorise five chemically different sulphonic azo synthetic dyes was evaluated under the operating conditions which had already been optimized. An increase in the initial dye content, led to a slow decrease in the decolorisation efficiency. Sequential batch culture studies were performed in the laboratory for the long-term utilization of this fungus, to decolorise the individual dyes over repeated exposure (respike) of four cycles of 8 days each. The fungus showed high decolorisation capacity and was able to tolerate high concentrations of the dyes and sustain the decolorisation process for long. Under sequential batch reactors, very high degrees of decolorisation of the four reactive dyes were repeatedly achieved. The decolorisation potential of the fungus could be correlated to the glucose consumed by the fungus as well as the structure of the dyes. Dyes with a naphthalene di sulphonic chromophore having the SO(3)H group para to the azo bond were easily degraded compared to the dyes with a benzene disulphonic acid chromophore which was difficult to degrade. (C) 2010 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers.