Uniform Au nanoparticles were synthesized by a simple process, mixing HAuCl4 and N,N-dirnethylacetoacetamide. These nanoparticles were characterized by UV-Vis, TEM, and EDX. N,N-dirnethylacetoacetamide was effectively used as a reducing agent and stabilizing agent as well. The reaction temperature played an important role in the size-selective and shape-selective An nanoparticle formation. The Au spherical nanoparticles obtained at room temperature had diameters of similar to 100 nm whereas the spherical, triangle, square, and hexagonal shape mixtures were obtained at 100 degrees C with diameter range of similar to 20 nm. (c) 2005 Elsevier B.V. All rights reserved.