Supported metal nanoparticles have been fabricated using electron beam lithography (EEL) and pulsed laser deposition (PLD). EEL produced ordered two-dimensional arrays with particle diameters of 40 +/- 0.5 nm, uniform interparticle distances (230 +/- 2 nm), and uniform height (20 +/- 0.5 nm). Due to the narrow size distribution of the particles and the long-range (cm(2)) order, the arrays produced using EBL were applied as models for supported metal catalysts. Smaller particle sizes can be obtained using PLD, but with larger size and spatial distributions of the particles. Particles fabricated with PLD have mean sizes ranging from 2 to 50 nm, depending on the ambient pressure during deposition. Tile nanoparticles have been characterized using TEM, AFM, UPS, and SEM. Reaction studies of ethylene hydrogenation on Pt nanoparticle arrays have demonstrated that detectable amounts of ethane are produced, despite the low surface area of the model catalysts.