Peroxiredoxins (Prxs) play important roles in antioxidation and cell signaling. A gene encoding a novel 2-Cys Prx was identified based on sequence homology in an expressed sequence tag database of the Antrodia camphorata, a medicinal mushroom found only in Taiwan. The 2-Cys Prx cDNA (940 bp) encodes a protein of 188 amino acid residues with calculated molecular mass of 20,965 Da and a pI of 5.89. The coding region was subcloned into pAVD10, transformed into Escherichia coli, and expressed as a His-tagged fusion protein. The purified enzyme was characterized under various conditions. The Prx retained 68% activity after being heated at 60 degrees C for 2 min. It was stable under a broad pH range from 5 to 11. The enzyme activity was slightly decreased in the presence of 1% sodium dodecyl sulfate. The enzyme was somewhat susceptible to chymotrypsin treatment but resistant to digestion by trypsin.