AbstractThe compositions of alkaline extractives in bamboo sulfonated chemi-mechanical pulps (SCMP) were analyzed by UV spectroscopy and gas chromatography-mass spectrometry (GC-MS), and their effects on peroxide bleaching were studied. The extractives were composed of short-chain aliphatic compounds, phenols, and fatty acids, of which phenols were the major components. The amount of extractives was increased with the dosage of NaOH, and correspondingly, the bleachability of the extracted pulp was improved. When 3.5% NaOH was used, the brightness gain was 5.83%ISO, and the post-color (PC) number was decreased by 55.7%. The phenol compounds, which might easily generate conjugated structures, may play an important role in bleachability of bamboo SCMP and brightness stability of pulp.