Heterogeneous catalysis is a large and important field of research, and is especially of interest to the project sponsors Johnson Matthey (JM). This EngD project focused on studying catalytic materials of interest to JM in order to investigate the metal support interaction and determine the effects of various reaction conditions. The key techniques used in this work are synchrotron radiation based, such as X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) as well as combinations of techniques. A variety of catalytic materials have been investigated using synchrotron X-ray techniques and conventional laboratory analytical techniques. Understanding these processes will allow for the tailoring of catalyst design and modification of support materials that will lead to improved and more efficient catalytic materials in the future. Supported platinum group metals were studied during reduction using in situ XAS. The materials were prepared through sequential deposition on an alumina support of first the platinum group metal then a ceria layer; this additional layer of ceria was deposited to cover the metal particles, limiting movement and gas transfer processes. The effect of the MSI on the reduction of Pd nanoparticles supported on a variety of inorganic materials in order to determine the structure of metal particles was also explored using in situ XAS. A combination of the LIII- and K-edge analysis was utilised to provide a better understanding of metal support interaction and the changes in the electronic structure for supported Pd nanoparticles. Other materials investigated include zinc oxide nanoparticles, which are important for a variety of applications due to their semi-conductor properties. Additionally AuCu bimetallic clusters were investigated in situ during reduction, calcination and during the catalytic oxidation of propene. The use of XAS allowed for the probing of the extent of the metal alloying and the effect on the propene catalysis.