Nascent volatiles from the pyrolysis of a type of woody biomass were reformed in a bed of charcoal at 750-850 degrees C. While the volatiles passed through the bed together with air at an air ratio of 0.115, the concentration of heavy tar (bp > 336 degrees C) decreased from 910 000 to 6-1020 mg/Nm(dry)(3). This rapid and almost total decomposition of the tar can be ascribed to its deposition onto the charcoal surface, forming coke, The coke formation leads to the loss of the charcoal micropores that provide active sites. Therefore, simultaneous creation of micropores by gasification is necessary to maintain the charcoal activity. Steam played the role of gasifying agent, while O-2 was consumed mainly by gas-phase oxidation that supplied the heat for the reaction.