A number of aspects of using large bubble columns for cumene oxidation were investigated in both laboratory and production reactors. Based on the dispersion model with an axial dispersion coefficient of 0.2 m(2)/s and a radial dispersion coefficient of 0.034 m(2)/s it is shown that for typical reaction conditions at a superficial gas velocity of 2 cm/s the liquid phase is almost ideally mixed. In addition some experimental Work and simulations with Computational Fluid Dynamics CFD were conducted on free convection heat transfer in a non-aerated reactor to calculate the so-called Self-Accelerating-Decomposition-Temperature (SADT).