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The transition into greener and more sustainable chemical manufacturing processes necessitates the development new generations of heterogeneous catalysts. The selective oxidation of organic molecules is a class of reaction of paramount importance to the chemical industry as it enables the production of epoxides, alcohols, aldehydes and other important oxygenates. Metal nanoparticles (NPs) consisting of several hundreds or thousands of atoms possess unique properties which are often drastically different from the bulk state properties. This is particularly true for Au NPs, which have recently been shown to exhibit high catalytic activity for a range of reactions. The present thesis investigates the design of nanostructured Au-based catalysts and their performance in selective oxidation reactions. Using advanced synthesis and characterization techniques has enabled the fabrication of novel and highly active Au-based catalysts. Monometallic and bimetallic Au-Pd colloidal NPs with various atomic compositions have been synthesized and immobilized on titania and ceria nanostructures. The new catalysts were tested in the selective oxidation of benzyl alcohol and glucose, and were found to be substantially more active than similar catalysts reported in the literature. The catalytic activity and product selectivity were found to be strongly dependent on the Au-Pd particle size, composition, and the morphology and physiochemical properties of the support. In the selective oxidation of glucose over AuxPdy/titanate nanotubes, a new linear correlation between the concentration of Au in the alloyed Au-Pd NPs and the formation of deep oxidation products was discovered. Amongst the various ceria nanostructured supports examined, ceria nanorods (Ce-NR) were found to give the most active Au-Pd catalysts. The exceptional catalytic activity and stability of Au-Pd/Ce-NR in benzyl alcohol and glucose oxidation was ascribed to the high oxygen activation potential of Ce-NR and its ability to stabilize finely dispersed colloidal Au-Pd NPs on its exposed facets and defect sites. Characterization of the various catalysts by TEM, STEM, STEM-EDX, XPS and XRD provided invaluable insights into the structure-activity relationship in supported Au-Pd catalysts, which helped in optimizing catalyst design. This thesis has also shed light on some fundamental aspects in the selective oxidation of hydrocarbons in the liquid phase with Au catalysts.