Rapid microwave pyrolysis has been applied to a relatively large piece of larch (60 mm diameter and 60 mm height), namely a piece of lumber, within a short irradiation time. The yields of charred residue and tar were about 39 to 35%, and 20%, respectively, after 6 to 8 min of microwave irradiation. Based on the dry weight of the wood, an overall yield of 2.4% of levoglucosan was obtained. The specific surface area of the charred residue obtained from the central region of the wood was 550 to 655 m(2).g(-1). This surface area is much greater than that of char produced by a conventional carbonization process.