Dark fermentation of textile wastes is discussed in the paper. In the experiment were used cotton wastes. Before fermentation the cotton was hydrolyzed using 0.1 M of HCl. The inoculum was pretreated using heat shocked for 0.5 h at temperature of 105°C. The fermentation was carried out under conditions: load 5 g/l, pH in the range 5 by 0.1 M of HCl, and oxygen in small quantities was added. The oxygen flow rates (OFR) was 0.008 ml/h.. The fermentation was carried out at temperature of 40 °C for one day. In reactors with pretreated inoculum (pH 5) biogas was detected and its content (hydrogen carbon monoxide, carbon dioxide and nitrogen) were determined. Methane was not produced during experiment. The volume of hydrogen for process performed at temperature 40°C 0.168 dm3 of at biogas content 43%.