Room-temperature synthesis of Pd nanoparticles protected by polyvinylpyrrolidone (PVP) has been successfully achieved by merely adding sodium hydroxide (NaOH) acting as accelerator for the reduction of Pd(II) in ethylene glycol (EG) Without any externally added reducing agent. The Pd particle sizes were coil trol led in the range from 8.6 to 2.4 nm by changing the concentration of NaOH from 0 to 3.2 x 10(-1) M. The particle formation was monitored by UV-vis spectroscopy and the microstructure of Pd nanoparticles was analyzed by TEM and XRD. The product 017 adding NaOH in EG was characterized by FTIR and a -CHO group which possesses reductive ability was identified. Ill addition, the prepared Pd nanoparticle could serve as an effective activator for electroless copper deposition (ECD) on epoxy substrate, which is an essential process in the printed circuit board (PCB) industry. In contrast to existing commercial activators, the new activator shows superior stability and excellent performance for ECD. (c) 2005 Elsevier Inc. All rights reserved.