We modelled the production of hydroxy fatty acids from oleic acid by Pseudomonas aeruginosa 42A2 in a bioreactor with a non-dispersive aeration system. First, we designed an adapted wetted-wall gas-absorption column, offering a k (L)a value of 39.9 h(-1), to enhance oxygen absorption in the culture media and prevent foam formation. Then, we analysed different kinetic models to simulate the yield coefficients and the kinetic constants in this bacterial transformation. Monod model fitting (mu (max1) = 0.51 h(-1), K (S1) = 1.60 C-mol l(-1), mu (max2) = 0.12 h(-1), K (S2) = 0.035 C-mol l(-1), and k (2) = 0.033 h(-1)) showed a good accuracy with the experimental data sets and was chosen for its simplicity. Lastly, mass balances were carried out to establish the stoichiometry of this biotransformation with the following yield coefficients, Iyen (X/OA), Iyen (X/(10S)-HPOME) and Iyen ((10S)-HPOME/(7S10S)-HPOME) of 0.172, 0.347 and 2.388 C-mol C-mol(-1), respectively.