AbstractContinuous and batch tests were conducted to evaluate fermentative biohydrogen production from starch wastewater via a mesophillic up-flow anaerobic staged reactor (UASR). The effects of organic loading rate (OLR) and food to micro-organisms ratio (F/M) on hydrogen yield (HY) and hydrogen production rate (HPR) were investigated. The bioreactor was continuously operated at a constant hydraulic retention time (HRT) of 6.7 h. The optimal OLR and F/M ratios were 54 g-COD/L.d and 1.4 g-COD/g-VSS.d, respectively. The maximum HY and HPR were 1.87 mol-H2/mol-glucose and 246 mmol-H2/L.d, respectively. Batch experimental results indicated that the optimal initial cultivation pH ranged from 5.5 to 6.5 with a hydrogen potential (P) of 1435-1420 mL-H2, while the initial substrate concentration of 20 g-starch/L showed a maximum HPR (Rm) of 300 mL-H2/h. Zero, 1st and 2nd order kinetic studies were used to develop a model of the experimental data. The 2nd order model adequately fitted with the experimental results (R2>0.97) better than those for a zero- or a 1st order kinetic reaction.