The extremely thermostable wild type and recombinant beta-glucosidases, from Pyrococcus furiosus, served as catalysts for the biotransformation of new glucoconjugates at elevated temperatures. In conversion experiments using the transglucosylation approach, the free or immobilized enzyme accepted primary and even tertiary organic alcohols, as well as primary and secondary artificial organosilicon alcohols, as aglycones. Cellobiose served as the glucose donor. The products obtained were purified by liquid chromatography and analyzed. Using beta-glucosidase a wide variety of products were synthesized. Due to the very broad structural diversity of the aglycones linked to the 1-beta-O-D-glucose, this beta-glucosidase seems to be a useful biocatalyst for regio- and stereoselective sugar derivative synthesis.