This study investigated the feasibility to produce biohydrogen of a mechanically stirred anaerobic sequencing batch biofilm reactor (AnSBBR) treating sucrose-based synthetic wastewater. The bioreactor performance (30 A degrees C) was evaluated as to the combined effect of fill time (2, 1.5, and 1 h), cycle length (4, 3, and 2 h), influent concentration (3,500 and 5,250 mg chemical oxygen demand (COD) L-1) and applied volumetric organic load (AVOL(CT) from 9.0 to 27.0 g COD L-1 d(-1)). AVOLs were varied according to influent concentration and cycle length (t (C)). The results showed that increasing AVOL(CT) resulted in a decrease in sucrose removal from 99 to 86 % and in improvement of molar yield per removed load (MYRLS.n) from 1.02 mol H-2 mol carbohydrate(-1) at AVOL(CT) of 9.0 g COD L-1 d(-1) to maximum value of 1.48 mol H-2 mol carbohydrate(-1), at AVOL(CT) of 18.0 g COD L-1 d(-1), with subsequent decrease. Increasing AVOL(CT) improved the daily molar productivity of hydrogen (MPr) from 15.28 to 49.22 mol H-2 m(-3) d(-1). The highest daily specific molar productivity of hydrogen (SMPr) obtained was 8.71 mol H-2 kg TVS-1 d(-1) at an AVOL(CT) of 18.0 g COD L-1 d(-1). Decreasing t (C) from 4 to 3 h decreased sucrose removal, increased MPr, and improved SMPr. Increasing influent concentration decreased sucrose removal only at t (C) of 2 h, improved MYRLS,n and MPr at all t (C), and also improved SMPr at t (C) of 4 and 3 h. Feeding strategy had a significant effect on biohydrogen production; increasing fill time improved sucrose removal, MPr, SMPr, and MYRLS,n for all investigated AVOL(CT). At all operational conditions, the main intermediate metabolic was acetic acid followed by ethanol, butyric, and propionic acids. Increasing fill time resulted in a decrease in ethanol concentration.