We report on the detailed analysis of chemical modifications and structural changes in the cellulose and lignin of Populus tremula (a hardwood) and Buxus sempervirens (a softwood), as a result of photodegradation in a Xenon test chamber. The results obtained by means of FTIR spectroscopy indicate that lignin is the most sensitive component to the degradation process for both woods examined. On a structural level, the virtual elimination of the amorphous cellulose was observed for both types of wood. The crystallised cellulose I component, which accounts for the whole crystalline phase, undergoes minor structural changes, this effect being more important in the case of Populus tremula that was less degraded than Buxus Sempervirens.