Dark fermentation has the potential to produce biohydrogen using raw material waste, such as wastewater from the corn industry (cornWW), which is characteristically alkaline and improperly discharged. This study aimed to assess the impact of different hydraulic retention times (HRT) on hydrogen production in a sequencing batch reactor system using raw cornWW as feedstock. Different HRTs were evaluated (4, 2, and 1 day(s)). Higher biohydrogen productivity was observed in HRT value of 1 day (893.6 ± 10.1 NmL H