MOF stands for metal-organic frameworks. They are hybrid porous solids with a geometrically well-defined structure that can be tailored, both in shape and size, to many different applications. Such applications include gas storage, gas purification and gas separation as well as heterogeneous catalysis. A disadvantage with most MOFs is their low thermal and chemical stability. UiO-66 is a Zirconium-containing MOF published in 2008 and patented by the University in Oslo. It is one of the most stable MOFs that have been synthesized to date, making it a good candidate for the previously mentioned applications. Even though this MOF has been published much, a systematic analysis of the parameters of synthesis has been lacking. The basis of this master`s thesis is to investigate some of these parameters.The method used for investigating this was to run series of syntheses while changing just one parameter at a time and characterizing the products using PXRD, TGA, SEM and EDS. The parameters investigated were washing procedures, adding a competing ligand, temperature and concentration of water, DMF, HCl and linker.