The aim of this work was to determine easily and quickly the operating conditions for the industrial production of lactulose (rate of isomerisation, rate of lactose degradation, reaction time, temperature, pH). The kinetic equations of lactulose formation and lactose degradation in an alkaline medium (NaOH) were determined. Experiments were carried out at different OH- concentrations (0.5 x 10(-2)-19 x 10(-2) mol dm-3) and at different temperatures (328-353 K). A kinetic model is presented which can be used to describe the experimental results and hence a procedure for industrial production.