The production of vinegar in an aerated-stirred reactor was modelled using a hybrid approach. The growth rate was modelled according to the total biomass specific growth rate, mu(g)v, which represents the growth of an active biophase and the fraction of cells which are growing. A quadratic model based on the process variables, i.e. hydrostatic pressure, ethanol concentration, aeration, agitation and temperature. was developed for mu(g)v and the substrate and product kinetics were related mechanistically to the growth rate, including the kinetics of acetoin and ethyl acetate production. This model was coupled with the models for oxygen transfer and gas-liquid transfer, reported in a previous study, and the prediction capacity of the system of equations was validated by simulating semi-continuous and continuous real processes developed in a pilot fermentor. (C) 2008 Elsevier Ltd. All rights reserved.