A fatty acids omega hydroxylation biocatalytic process into an intensified liquid-liquid slug flow microreactor with immobilized or aqueous solution-phase enzyme was proposed and analyzed numerically. Hydroxylation of the tetradecanoic acid by the recombinant P450foxy enzyme produced by an Escherichia coli was chosen as a case study. The liquid-liquid reaction system includes an aqueous continuous liquid phase containing buffer, cofactor, and enzyme (when biotransformation occurs in aqueous phase) and an organic dispersed liquid phase which behaves as a substrate (tetradecanoic acid) reservoir facilitating a constant mass transfer between the organic dispersed and aqueous continuous liquid phases without deactivating the enzyme. The behavior of the intensified microreactor was analyzed through simulation via two-scale, isothermal, unsteady-state models accounting for detailed hydrodynamics, whereupon were tied the thermodynamics and kinetics of fatty acid hydroxylation catalyzed by immobilized or aqueous solution-phase P450foxy enzyme. The effects of key operating parameters as well as the contribution of P450foxy enzyme on the performance of fatty acid hydroxylation process are highlighted. The intensified microreactors with liquid-liquid reaction systems offer a promising option for the fatty acids hydroxylation biocatalytic process because of high specific enzymatic activity as a result of the constant mass transfer of the substrate between the dispersed organic and continuous aqueous liquid phases.