Catalysts lower energy costs of a wide range of important processes, from the production of oil and plastics to the preparation of drugs and paints, making these products affordable. The search for new catalysts is vital as they allow otherwise expensive if not impossible products to be made. Metal organic frameworks (MOFs) are modular compounds, the structures of which can be readily tuned for use as catalysts. UiO-66 has been of great interest and we have shown the use of the Ce(IV)-form in catalytic reactions. Activation of UiO-66 involves heating the MOF to high temperature to remove water (and hydroxyl groups) from the structure. However in UiO-66 compounds made with Zr(IV), this causes additional changes in the structure. We will systematically investigate how different metal compositions of the MOF influence these structural changes to optimise UiO-66 for catalytic applications.