Abstract Biological decolorization of textile dyestuff Basic Blue 22 (C.I. 61512), a phthalocyanine type reactive dyestuff, by the white-rot fungus Phanerochaete sordida ATCC90872 was studied in a rotating biological contactor (RBC). The effects of different operating parameters including disc type, rotational speed, glucose and dyestuff concentration on the decolorization performance of white-rot fungi were investigated. The system was operated in repeated-batch mode with 48 h hydraulic retention time. Three different disc types; plastic, metal mesh covered plastic discs and metal mesh discs were used and the plastic disc was found to be most suitable. The highest decolorization efficiency was obtained with a rotational speed of 40 rpm. Minimum glucose concentration for 78% decolorization efficiency was 5 g/l. TOC removal efficiency was around 80% for 50–200 mg/l initial dyestuff concentrations and decreased to 52% for 400 mg dyestuff/l.