The study of heterogeneous catalysts by in-situ methods has compiled solid evidence that their function is intimately connected to a dynamic response of their precursor structure to the chemical potential of the reacting environment. This is also valid for the supra-molecular or mesoscopic dimension at which the performance of catalysts is decided critically by transport phenomena of molecules and energy. This mesoscopic dimension is well accessible by modern field emission SEM instrumentation. With advent of the ESEM technology it became conceivable to observe catalysts at truly near-ambient pressure conditions at work. As it turns out there are still obstacles to be overcome having to do with imaging conditions and the sample environment. We succeeded in modifying a commercial instrument such that we can observe simultaneously the catalytic activity of a specimen and its morphology. This is possible for complex reactions such as the epoxidation of ethylene over silver and for harsh conditions such as the CVD synthesis of grapheme over metal catalysts. The contribution uses these two examples to illustrate the value of insights one can obtain from such kind of in-situ microscopy. The results will be combined with insights gained from NAP XPS experiments that can be conducted under identical pressure-and temperature conditions. Together one obtains a combined picture of the geometric and electronic structure of working catalysts illustrating the hitherto barely detectable structural dynamics.