Membrane two-phase bioreactor is an interesting arrangement to carry out the reaction with the reactants of hydrophilic and hydrophobic features. The paper presents the mathematical model of membrane two-phase bioreactor working under steady- and unsteady- state conditions that describes the concentration changes of reactants in both phases positive verified with data of enzymatic dipeptide ZAlaPheOMe synthesis by the use enzyme - thermolysin, in two-phase ethyl acetate - water system.