In this paper the synthesis of stable palladium nanoparticles (PdNPs) by electrochemical methods at room temperature is reported. Direct electroreduction of H2PdCl4 aqueous solution in the presence of poly(N-vinyl-2-pirrolydone) (PVP) onto platinum electrodes was performed by the application of a constant current density pulse. By simultaneous stirring of the electrolyte, the NPs formed on the electrode surface were stabilized with PVP in the solution. The resulting PdNPs were characterized by transmission electron microscopy and the total content of palladium was analytically determined by atomic absorption measurements. The average size of the NPs (in the range of 10-22 nm) was tuned by changing the current density applied. The PdNPs prepared by this methodology exhibited highly efficient catalytic activity on Suzuki-Miyaura coupling reaction in aqueous medium. Particularly high turnover numbers (TON up to 10(4)-10(5)) were achieved by these PVP-stabilized PdNPs with aryl iodides and bromides. (c) 2012 Elsevier B.V. All rights reserved.