Sucrose monoesters of a fatty acid were synthesized by using lipase in a solvent-free system. When lipase from Mucor miehei was used as a catalyst with capric acid as the donor and sugar as the acceptor, sucrose 6-monocaprate was predominantly produced in a yield of 25.3%. The yield of product was significantly increased by the direct addition of a suitable pair of solid salt hydrates to the reaction mixture to control the water activity (a(w)). Among the salt hydrate pairs investigated, the barium hydroxide, 8/1H2O pair resulted in the highest yield of the product. This salt addition method was also successfully employed for acylation of primary hydroxyl groups in various unprotected mono- and disaccharides such as glucose, galactose, fructose, trehalose, mannose, maltose, and lactose.