Synthesizing nanoparticles from transition metal complex precursors has become the new trend in inorganic chemistry. One of the most vital objectives of nanotechnology is to harness the effects of scaling down to nano-sizes. This research book reviews the synthesis of nanoparticles, especially from metal complex precursors. It also discusses the applications of metal-oxide nanoparticles in catalysis and photocatalytic degradation of organic dyes. The book also leads to a discussion on the attempts to understand the nature of palladium nanoparticles as catalyst in cross-coupling reactions.