Firstly, the potential of barley bran, a common waste from the brewing industry, as a support-substrate for laccase production by the well-known laccase producer Trametes versicolor under solid-state conditions was assessed. The effect of the initial ammonium concentration on laccase activity was also studied. Operating with barley bran at an initial ammonium concentration of 0.2 g/l, laccase activities were enhanced by 13-fold in relation to inert support cultures. Secondly, laccase production by T versicolor and the newly isolated Trametes hirsuta grown on barley bran was improved by supplementing the cultures with 2,5-xylidine and copper sulphate. Thus, laccase from T hirsuta cultures supplemented with both 1 mM copper sulphate and 2 mM xylidine was enhanced 5-fold. Finally, the in vitro decolourisation of several synthetic dyes by the extracellular liquid produced by T hirsuta cultures was carried out. Decolourisation was more effective at pH 4 than 5. High decolourisation percentages in short incubation times were achieved for Bromophenol Blue, Indigo Carmine and Methyl Orange, whereas Poly R-478 presented much more resistance to degradation. (C) 2003 Elsevier Ltd. All rights reserved.