The selective oxidation of ethene over a silver on ¿-alumina catalyst was studied in a wall cooled tubular reactor. Temperatures were measured inside the bed at different axial and radical positions as well as the overall conversion and selectivity. Locally measured temperatures vary after repacking the bed whereas the global properties do not vary. Angular variations in temperature cannot be described by present day models. The steady state temperature profiles in the packed bed and overall conversion and selectivity as function of different operating conditions are discussed.