Starch gelatinization and enzymatic hydrolysis was carried out in a continuous Couette-Taylor flow reactor with a water jacket. The degree of gelatinization and the concentration of reducing sugars produced via enzymatic saccharification were evaluated by varying operational variables: rotation speed of an inner cylinder, initial concentration of starch and reaction temperature. At the initial concentration of the starch suspension, 50 kg m(-3), starch saccharification proceeded sufficiently even at low rotation speed of the inner cylinder and saccharification temperature. At the higher initial concentration, 100 and 150 kg m(-3), a higher rotation speed of the inner cylinder and temperature of the saccharification section were required to obtain sufficient starch saccharification. Even in the case of C-0 =100 and 150 kg m(-3), the more reducing sugar was obtained by choosing an adequate rotation speed of the inner cylinder and a reaction temperature. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.