Endo-beta-1,4-glucanase from Aspergillus niger was found to have an endo-type transglycosylation activity. The enzyme effectively transferred cellooligosaccharide residues to various 1-alkanols in the presence of cellopentaose as the oligosaccharide donor. By incubating the enzyme with 1-octanol and cellopentaose in the presence of acetonitrite, 1-octyl-cellotrioside was synthesized. The product was isolated by silica gel column chromatography and analyzed by mass spectrometry. p-NP-beta-Glc, p-NP-beta-Gal, p-NP-beta-GlcNAc, Ser, and Thr were also possible accepters for the transglycosylation activity of the enzyme.