A peroxidase (DyP) involved in the decolorization of dyes and produced by the fungus strain Geotrichum candidum Dec 1 was purified. DyP, a glycoprotein, is glycosylated with N-acetylglucosamine and mannose (17%) and has a molecular mass of 60 kDa and an isoelectric point (pI) of 3.8. The absorption spectrum of DyP exhibited a Soret band at 406 nm corresponding to a hemoprotein, and its Na2S2O4-reduced form revealed a peak at 556 nm that indicates the presence of a protoheme as its prosthetic group. Nine of the 21 types of dyes that were decolorized by Dec 1 cells were decolorized by DyP; in particular, anthraquinone dyes were highly decolorized. DyP also oxidized 2,6-dimethoxyphenol and guaiacol but not veratryl alcohol. The optimal temperature for DyP activity was 30 degrees C, and DyP activity was stable even after incubation at 50 degrees C for 11 h.