Synthesis of propyl-β-d-galactoside with β-galactosidase from A. oryzae was optimized by RSM. A. oryzae β-galactosidase was immobilized in agarose supports and by crosslinking and aggregation. Highest yield (0.87 mol/mol) was obtained with the enzyme immobilized in glyoxyl-agarose. Cumulative productivity of the glyoxyl-agarose derivative doubled that of the free enzyme. An enzymatic procedure to obtain pure propyl-β-d-galactoside has been developed.