There is a strong pressure on the chemical sector to develop low waste routes, with a minimum number of process steps, for production of high added value chemicals. Especially pharmaceutical production asks for products that are free of metal traces or residues of reactants, and isomerically pure. This provides a strong driver to invent new routes that activate C-H bonds, e.g. in aromatic molecules. However, aromatics often contain several C-H bonds, among which most catalysts do not discriminate. Consequently, most homogeneous catalysts (e.g. Pd) produce undesirable mixtures of isomeric product molecules. We have now discovered that in a shape-selective Pd-zeolite, the C-H activation proceeds so as to form predominantly the (often desired) para-isomer. Moreover, the heterogeneous zeolite catalyst solves the problem of product contamination by metals. The project seeks to understand the fundamentals of this breakthrough C-H activation technology, by combining experimentation and advanced modelling, to answer three research questions: 1) how are the arene C-H bonds activated ? 2) can we understand the dynamics of the intrazeolite Pd-aryl species ? and 3) how does the shape selectivity work ? Ultimately, computation will predict the most shape-selective zeolites for C-H activating reactions that were previously not studied experimentally.