AbstractEthanol production in a simultaneous sacchariﬁcation and fermentation (SSF) process using waste textiles as feedstock was studied. The dissolution pretreatment of waste textiles in ortho-phosphoric acid resulted in at least 2 fold improvement in enzymatic hydrolysis rate and reducing sugar yield. The reducing sugars obtained from dyed or discolored waste textiles by cellulase hydrolysis demonstrated no inhibitory effect on ethanol fermentation activity of Zymomonas mobilis employed in SSF. SSF with a high waste textile loading (75 g L-1) could still be operable due to the fast liquefaction of the pretreated substrate via enzymatic hydrolysis. Approximately 50 g L-1 ethanol was achieved within 24 h. In addition to 100% cotton textiles, the 40/60 polyester/cotton (T/C) blend waste textile could also be pretreated under the same condition to achieve the comparable ethanol production yield (~0.4 g EtOH g-1 glucose) from its cotton fraction in SSF.