A mathematical model describing sucrose esters synthesis in biphasic di-n-phentyl ether - water system by lipase from Mucor circinelloides has been elaborated. This model considers correlation between physicochemical factors, dependent on the solvent, substrates, products and temperature, catalytic factors corresponding to the relationship between lipase and the physicochemical factors of the model (Ko=F(A)), as well quantitative factors whose values may be regulated during the reaction (substrate concentration, phase volume coefficient (A) and water concentration). This model was confirmed by syntheses of caprylic and oleic sucrose esters. The maximum reaction yield for the synthesis of caprylic sucrose ester calculated on the basis of the elaborated model was 67,5% and experimental value was 67,8% for A = 44. For oleic sucrose ester, the theoretical and experimental yields of synthesis, were 71,9% and 70,5% respectively. Using this model it is possible to estimate the maximum achievable (in particular conditions) yield of the ester synthesis. It can also be applied for simulations enabling evaluation of the effect of the particular factors on the yield of ester synthesis and resulting optimisation of selected factors in the reaction system. The simulations were performed for two factors of the model in three dimensional space. It was found that the ester synthesis was mostly affected by the following invariable factors: partition coefficients of products (PE, PW) and phase volume coefficient (A). The concentration of water in the water phase and the partition coefficients of sugar (PAL) influenced the yield to a smaller extent.