Batch anaerobic studies were conducted to study the effect of ultrasonication as a pretreatment method for pulp waste prior to anaerobic hydrogen production. Pre-treatment was conducted by sonicating a 100 mL of pulp waste at different sonication times varying from 0.5 min to 30 mm. The ultimate hydrogen production increased with increasing sonication time. The highest ultimate hydrogen production was achieved at a sonication time of 30 min and reflected an 88% increase over the unsonicated food waste, of 80 mWg VSadded. The highest final VFAs concentration after fermentation (corresponding to 70% increase over the unsonicated food waste) was also achieved at a sonication time of 30 min. There were no significant differences between the acetate-to-butyrate ratios (HAc/HBu) for the all sonication times. The maximum hydrogen production rate at sonication time of 30 min was about 145% higher than that the unsonicated food waste. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.