This study investigated the conversion of Lemna minor biomass to bioethanol. The biomass was pre-treated by steam explosion (SE, 210 degrees C, 10 min) and then subjected to simultaneous saccharification and fermentation (SSF) using Cellic (R) CTec 2 (20 U or 0.87 FPU g (1) substrate) cellulase plus beta-glucosidase (2 U g (1) substrate) and a yeast inoculum of 10% (v/v or 8.0 x 10(7) cells mL (1)). At a substrate concentration of 1% (w/v) an ethanol yield of 80% (w/w, theoretical) was achieved. However at a substrate concentration of 20% (w/v), the ethanol yield was lowered to 18.8% (w/w, theoretical). Yields were considerably improved by increasing the yeast titre in the inoculum or preconditioning the yeast on steam exploded liquor. These approaches enhanced the ethanol yield up to 70% (w/w, theoretical) at a substrate concentration of 20% (w/v) by metabolising fermentation inhibitors. (C) 2015 The Authors. Published by Elsevier Ltd.