Lipases from several origins-in soluble form or immobilized on solid supports of different aquaphilicity-have been used for the production of mono- and di-oleylglycerol by hydrolysis of sis of triolein. The porcine pancreatic lipase adsorbed on Celite was Sound to be the most effective biocatalyst tested. High activity and excellent selectivity toward the formation of intermediate acylglycerols were achieved (the conversion to diolein plus monoolein was 79% after 5 h of reaction). The time course of triolein hydrolysis with free and immobilized lipases was analyzed using a sequential kinetic model, and the apparent first-order rate constants were calculated The differences found in the rate constants were related to differences in the regioselectivity of the enzymes and/or the aquaphilicity of the supports.