Abstract: Catalysis remains an important field of research that drives economical approaches for various energy conversion applications from natural resources. Industrial catalyzed reactions occur at the surface of heterogeneous catalysts where many different active sites exist. Any atom not at the surface is not directly used to drive chemical reactions. To improve efficiency, catalytic materials have shrunk to the nano and atomic scale, increasing the surface area/volume ratio. Traditional characterization methods for nanomaterials provide a large scale picture of overall changes but do not exhibit a high degree of spatial information. To that end, transmission electron microscopy (TEM) may be used to probe materials down to the scale of individual atoms through both imaging and spectroscopy. Specialty holders allow for replication of benchtop reactions with which to investigate changes to nanomaterials in situ. Here, in situ TEM was used to gain insights into a variety of chemical processes including bond cleavage and surface reduction.