The production of phthalic anhydride (PA) by partial oxidation of o-xylene is an industrially important example of a strongly exothermic reaction proceeding with high rate. The PA productivity is restricted by the removal of heat, i.e. the extent of the hot spot with concomitant negative effects on the thermal stability, and by the pressure drop in the catalyst bed. – In this project, the application of novel, monolithic catalyst beds with low pressure drop and improved heat transfer is evaluated aiming for an increase in space-time-yield. The study comprises both, an extensive experimental investigation of the PA production over the novel catalyst using a pilot plant with a multisampling reactor, and the modelling of transport and reaction kinetics.