This work presents a novel approach to the controlled electrodeposition of metal nanoparticles at a liquid-liquid interface. It has been shown that the size of gold nanoparticles co-deposited in a polymer matrix (nanocomposites) can be varied (indirectly) by modification of the Galvani potential difference established at the water-1,2-dichloroethane interface. Two electrochemical systems with different aqueous monomers, namely tyramine and resorcinol were studied. Various partitioning ions were used to set the Galvani potential difference resulting in the production of gold nanoparticles of different size parameters. The average particle size of the nanocomposites increases with increasing interfacial Galvani potential difference and the relationship between the Galvani potential difference and the size of prepared nanoparticles follows a similar trend for both of the studied systems in the covered potential range of approximately 600 mV. The synthesised nanocomposites were analysed using transmission electron microscopy. (c) 2008 Elsevier Ltd. All rights reserved.