Pretreatment and saccharification of lignocellulosic materials is the key technology affecting the efficiency of cellulosic biohydrogen production. In this work, two pure cellulosic materials (i.e., carboxymethyl-cellulose (CMC) and xylan) were directly hydrolyzed (without pretreatment) by a cellulolytic isolate Cellulomonas uda E3-01 able to release extracellular cellulolytic enzymes. Natural cellulosic feedstock (i.e., sugarcane bagasse) was chemically pretreated prior to the bacterial hydrolysis.A temperature-shift strategy (35 °C for cellulolytic enzymes production and 45 °C for hydrolysis reaction) was used to increase the production of reducing sugars during the bacterial hydrolysis. The hydrolysates of CMC, xylan, and bagasse were efficiently converted to H 2 via dark fermentation with Clostridium butyricum CGS5. The maximum hydrogen yield was 8.80 mmol H 2/g reducing sugar (i.e., 1.58 mol H 2/mol hexose) for CMC, 6.03 mmol H 2/g reducing sugar (i.e., 0.91 mol H 2/mol pentose) for xylan, and 6.01 mmol H 2/g reducing sugar for bagasse.