Palladium nanoparticles with narrow size distribution were prepared by applying poly(ethyleneglycol) (PEG) and Pd(OAc)(2) in the absence of other chemical agents. PEG appeared to act as both reducing agent and stabilizer. The results of XRD show that the concentration of precursor played the key role to the development of palladium nanoparticles. The reduction of Pd2+ to nano Pd was sensitive to the chain length of the PEG, and the larger chain length PEG such as PEG 2000 exhibited higher reduction reactivity. The as-prepared palladium nanoparticles were found to be a highly stable and reusable catalyst for Heck reaction. (C) 2004 Elsevier B.V. All fights reserved.