Oligosaccharide synthesis by invertase increased from 3.1 to 12.1% (w/w) in medium containing 1.7 M sucrose and 60% (v/v) butyl acetate when 90 mM SDS was added. The main oligosaccharide synthesised has a MW of 504 Da and is made up of 2 fructose units and 1 glucose. Reversed micelles were not formed with SDS addition, but invertase activity was enhanced by over 30% in all the organic two-phase systems studied.