When using cellulosic biomass as feedstock for dark fermentative hydrogen production (DFHP), feedstock preparation is essential step for enhancement of biodegradability. In the present work, electric field was newly applied as a novel pretreatment technique to Laminaria japonica, a marine brown algae, as an alternative method for feedstock preparation. A feasibility test was first conducted (20-100 V for 30 min). The highest H-2 yield (93.6 mL H-2 g(-1) dry cell weight (dcw)) was achieved at applied voltage of 60 V, while the performance was decreased from applied voltage of 80-100 V due to increasing formation of hydroxymethylfurfural. Subsequently, electric pretreatment conditions (applied voltage and reaction time) were statistically optimized, and a H-2 yield of 102.7 mL g(-1) dcw was recorded with applied voltage 58.5 V and reaction time 30 min. This was 96.1% of the predicted value. These findings clearly revealed that the application of electric field as pretreatment method has enormous potential as an alternative method for feedstock preparation in DFHP. (C) 2014 Elsevier Ltd. All rights reserved.