Treatment of effluents from dye-based industries poses a major problem and biotreatment with white rot fungi seems to be a viable option. In this study, Phanerochaete chrysosporium, a commonly used white rot fungus, was used to biodegrade several synthetic dyes of varying structures, namely azo, anthraquinone, thiazine and vat dyes. The decolorization potential of P chrysosporium for seven dyes namely, Methyl violet, Congo red, Acid orange, Acid red 114, Vat magenta, Methylene blue and Acid green was studied. The effect of various operational parameters, namely dyes concentration (20-400 mg/l), pH (2-7), temperature (20-45 degrees C) and inoculum size (0.25-4 ml) on the maximum percentage decolorization were investigated. Studies were carried out using free cells and fungal cell entrapped calcium alginate beads of different sizes. The kinetics parameters 'K-dye' and 'V-dye (max)' for the decolorization process for all the seven dyes were estimated through Lineweaver-Burk plots. (c) 2005 Elsevier Ltd. All rights reserved.