Synthesis of 6-O-acylate-alpha-D-glycopyranose from underivatised substrates in anhydrous tert-butanol was achieved using immobilised lipases from Candida antarctica and Mucor miehei. Except for acetic acid, the initial reaction rates with the C. antarctica lipase were independent of acyl donor chain lengths and in a range of 3.9 +/- 0.4 mu mol glucose converted min(-1) g enzyme preparation. The catalytic activity of the M. miehei lipase increased with increasing acyl donor chain length with a maximum for stearic acid of 0.45 mu mol min(-1) g. Using maltose as substrate, the catalytic activity decreased by a factor of 48 and 20 with the lipase from C. antarctica and M. miehei, respectively, while with maltotriose no reaction was observed.