The application of Lipozyme (Termomyces lanuginosus) immobilized in gelatin gel in aliphatic ester synthesis was investigated taking the esterification of hexanoic acid with n-butanol as a model reaction. Conditions were optimized by factorial design and the highest conversion was obtained under the following conditions: molar ratio alcohol: acid of 2: 1, reaction time of 48 h and biocatalyst weight of 7.0 g. Under these conditions the esterification yield was around 98%. The operational stability of the immobilized lipase was assessed and results showed that after 12 batch runs, the enzyme showed no significant loss of activity.