The rational design of catalytically active materials requires detailed knowledge of the synthesis parameters that affect the nature and distribution of active sites. The goal of my research is to understand and quantify the reactions leading to the formation of active sites in order to control their subsequent reactivity. This study requires both detailed fundamental knowledge of the synthesis parameters that affect the nature of the reaction and experimental engineering skills including several chemical characterization and analysis. In my graduate work, I studied 1) the transformation of organogold precursor to gold nanoparticles, and 2) the reaction of homogeneous rhenium catalyst for olefin epoxidation. These catalysts have in common well-defined, molecular precursors and the use of kinetics to evaluate the formation of the active sites.