Enzymatic saccharification of pure a-cellulose was conducted in oscillatory baffled (OBR) and stirred tank (STR) reactors over a range of mixing intensities requiring power densities (P/V) from 0 to 250 Watts per cubic metre (W/m(3)). Both reactor designs produced similar saccharification conversion rates at zero mixing. Conversion increased with increasing mixing intensity. The maximum conversion rate occurred at an oscillatory Reynolds number (Re-0) of 600 in the OBR and at an impeller speed of between 185 and 350 rpm in the STR. The OBR was able to achieve a maximum conversion rate at a much lower power density (2.36W/m(3)) than the STR (37.2-250 W/m(3)). The OBR demonstrated a 94-99% decrease in the required power density to achieve maximum conversion rates and showed a 12% increase in glucose production after 24h at 2.36 W/m(3). (c) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.