A transesterification process for the production of esters of non-reducing sugars or sugar derivatives comprises reacting the sugars or sugar derivatives with a fatty acid alkyl ester in the absence of a solvent and at an elevated temperature, for example from 120 to 135.degree. C., by microwave radiation. The reaction is conducted in the presence of a potassium derivative soluble in the reaction medium, preferably a soap, and especially a soap of a C.sub.12 to C.sub.22 unsaturated or saturated fatty acid, for example oleic or stearic acid. The reaction proceeds to completion in relatively short time periods, with the result that the process may be conducted in air without the need for a gas blanket or vacuum, and without oxidation of the reactants or reversal of the reaction.