Glucansucrase from Leuconostoc mesenteroides was immobilized in 1 % (w/v) with sodium alginate to produce oligosaccharides. Glucansucrase gave three activity bands of approx. 240, 178, and 165 kDa after periodic acid-Schiff staining with sucrose. The immobilized enzyme had 40 % activity after ten batch reactions at 30 degrees C and 75 % activity after a month of storage at 4 degrees C, which is six times more stable than the free enzyme. Immobilized enzyme was more stable at lower (3.5-4.5) and higher (6.5-7.0) pH ranges and higher temperatures (35-40 degrees C) compared with the free enzyme. Immobilized and free glucansucrase were employed in the acceptor reaction with maltose and each produced gluco-oligosaccharide ranging from trisaccharides to homologous pentasaccharides.