In the frame of the development of a bioprocess using the competences of White Rot Fungi to decolourise and detoxify dye contaminated effluents, laccases were produced by the strain Pycnoporus sanguineus MUCL 41582 in a malt extract medium. Two isoenzymes were detected among which LAC-1 was concentrated. A survey of the composition of industrial effluents showed that wastewaters from textile industry usually contain high concentrations of Na2SO4 or NaCl. Regarding the activity profile of the biocatalyst against pH, salts, temperature and target substrates, LAC-1 appears to be a good candidate for application in acid dye bath treatments. Studying the model anthraquinonic dye ABu62 decolourisation, we proved that this dye was a good substrate for LAC-1. Furthermore, unusual kinetic behaviour was observed suggesting that LAC- I was activated in presence of ABu62. On the contrary, a classical Michaelis-Menten behaviour was observed for the oxidation of ABTS and LAC- I showed a high affinity for this substrate as compared to data available for other laccases. To our knowledge, this is the first report showing this atypical behaviour of a laccase in the presence of dyes. (c) 2007 Elsevier Inc. All rights reserved.