To characterize a novel alpha-glucosidase from the thermophilic fungus Malbranchea cinnamomea. The enzyme was purified to homogeneity with purification fold of 40 and a recovery of 7.2 %. It was a monomer with molecular mass of 65.7 kDa on SDS-PAGE. It was optimally active at pH 6 and 50 A degrees C (measured over 10 min) and exhibited a wide range of substrate specificity with the highest specific activity of 47.4 U mg(-1) for p-nitrophenyl alpha-d-glucopyranoside (pNPGlu) followed by isomaltose, panose and sucrose, suggesting that the enzyme belongs to the type I alpha-glucosidases. The K (m) values of the alpha-glucosidase for pNPGlu and isomaltose were 1.1 and 19.3 mM, respectively. Because of its unique properties, the alpha-glucosidase may have a potential in several industrial applications.