Catalysts,heterogeneous,homogeneous,andenzyme,areusuallynanoparticles.These areofvitalforthefunctioningof thehumanbody,forphotosynthesis,andforproducing fuels and chemicals in the petroleum and chemical industries. Interest in nanoscience and in nanotechnology in recent years has focused attention on the opportunity to develop catalysts that exhibit 100% selectivity for a desired product, thus removing byproducts and eliminating waste. This type of selective process is often called green chemistry or green technology. This book is the third Volume of Nanotechnology in Catalysis. It is mainly based on the symposium on Nanotechnology in Catalysis III which was held in fall 2004 at th the ACS 228 National Meeting in Philadelphia, PA. Several chapters were also from the authors who did not attend the symposium. We invited a few experts in the field to write on a topic which we see is needed to make the book comprehensive. It has been about 2 years since Volumes 1 and 2 were published. Many new contributions and breakthroughs have been made by researchers worldwide, showing the dynamics in the area of nanotechnology in catalysis.