Electron beam lithography (EBL),size reduction lithography (SRL), and nanoimprint lithography (NIL) have been utilized to produce platinum nanoparticles and nanowires in the 20-60-nm size range on oxide films (SiO2 and Al2O3) deposited onto silicon wafers. A combination of characterization techniques (SEM, AFM, XPS, AES) has been used to determine size, spatial arrangement and cleanliness of these fabricated catalysts. Ethylene hydrogenation reaction studies have been carried out over these fabricated catalysts and have revealed major differences in turnover rates and activation energies of the different nanostructures when clean and when poisoned with carbon monoxide. The oxide-metal interfaces are implicated as important reaction sites that remain active when the metal sites are poisoned by adsorbed carbon monoxide.