Geotrichum candidum Dec I, which exhibits a broad dye-decolorizing spectrum, was used to decolorize molasses during semi-batch cultivation. An eighty % decolorization of molasses and a stable peroxidase activity were maintained for approximately four weeks, after which, both activities deteriorated significantly. Subsequently, repeated batch cultivation of fungal cells immobilized on polyurethane foam was employed to solve the aforementioned problems and stable decolorization of molasses as web as stable peroxidase activity was realized for more than eight weeks.