Pyrolysis of NaOH-loaded Douglas fir and cellulose has been carried out to determine the effect of sodium hydroxide on the pyrolysis profile. A tar yield of 0 wt% and the char yield of 32 wt% were obtained at a final pyrolysis temperature of 500 degrees C. It was revealed that the amount of hydroxyl groups in the residue significantly decreased at 200 degrees C and that the structure of cellulose was distorted via crosslinking at the same temperature through spectroscopic analyses and diffraction patterns. The crosslinking led to the increase in char yield al 500 degrees C. A detailed analysis showed that char Yield from cellulose at 500 degrees C correlaled linearly with the degree of cross-linking calculated From the amount of dehydration at 200 degrees C. These results showed a possibility that the pyrolysis profile of biomass may be controlled through;in appropriate pretreatment to change the structure of the intermediate.