<P><B>Research highlights</B></P><P>► Hydrogen production in the alkalithermophile <I>Thermobrachium celere</I> was studied. ► Influence of chemo-physical parameters on H<SUB>2</SUB> production during glucose fermentation. ► Medium composition and pH affected the hydrogen production. ► A yield of 3.36mol H<SUB>2</SUB>/mol glucose was achieved at low hydrogen partial pressure. ► In optimal condition <I>T. celere</I> reached a hydrogen production rate of 20.7mmol H<SUB>2</SUB>/l/h.</P> <P><B>Abstract</B></P><P>In the present work the hydrogenesis in the anaerobic alkalithermophilic bacterium <I>Thermobrachium celere</I> was studied. The impact of several factors on hydrogen production during glucose fermentation was investigated in batch conditions. The optimal hydrogen production occurred at pH<SUB>67°C</SUB> 8.2 with phosphate buffer concentration of 50mM. Hydrogen yield reached the highest value of 3.36mol H<SUB>2</SUB>/mol glucose when the partial pressure in the gas headspace was reduced. Supplementation of nitrogen sources and iron affected hydrogen production. Under optimized conditions, the maximum H<SUB>2</SUB> accumulation and H<SUB>2</SUB> production rate were estimated to be respectively 124.3mmol H<SUB>2</SUB>/l culture and 20.7mmol H<SUB>2</SUB>/l/h. Considering the efficient and rapid hydrogen evolution, and the ability to grow in extreme environments, <I>T. celere</I> might be a good candidate for biohydrogen production in open (non-sterile) bioprocess system.</P>