The interesterification of olive oil with palmitic acid catalyzed by Rhizopus delemar lipase was investigated in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsions. The maximal reaction rate was obtained at a buffer pH of 5.0-6.5. The reaction rate also attained a maximum at a W (=[H2O]/[AOT]) value of 2-5 and a palmitic acid concentration of 125 mM. The molar percentage of the interesterified product 1,3-dipaimitoyl-3-oleoyl glycerol (POP) in the olive oil was markedly enriched from 2.8 to 22.7 mol% after 24 h of the reaction.