In order io determine the effects of smali teınperature fluctuations during the delignifîcation, a soft and a hardwood vvere delignified at slightly different temperatures from 70°C. W hile the yields of holocellulose as well as the cont.ent of klason lignin, acid-soluble lignin and alplıa cellulose, decreased at high temperature treatments, the carboxyl content in holocellulose contrarily increased. Any pentosan loss in oak holocelîuloses could not be detected vvhereas this loss in fir holocelîuloses was noticeable though the pentosan anıount in softvvood is quite low. By taking the yields of holocelluloses from different temperatures and their acid soluble- and klason lignin into account, the material balances were calculated, resulting in values of about 98-99% for softwood and 96-97% for hardwood. The slightly higher deficit in material balance for hardwood arises from the presence of tannins in wood, vvhich could not be removed during solvent extraction efficiently. Tlıen, during the delignifîcation the constituents of tannins becorne soluble causing ııncountable losses.