Abstract: A process for preparing 1-O-.alpha.-glucopyranoside-D-fructose by enzymatically converting sucrose is described, wherein a sucrose solution is brought into contact with free or immobilized, living or dead whole cells or with microorganisms forming the free or immobilized enzyme extract of isomaltulose from saccharose, the solution so treated being next subjected to chromatographic separation at ion exchangers or other suitable separation materials to obtain the 1-O-.alpha.-D-glucopyranosido-D-fructose as an aqueous solution which is then converted by methods known per se into the dry form.