Electroless deposition of Ag nanoparticles on PECVD SiNx:H dielectric layers is a new straightforward chemical bath process well adapted to the realization of plasmonic solar cells. Depending on the stoichiometry, SiNx:H contains a certain number of Si nanoclusters embedded in the silicon nitride matrix, that act as reducing agents for Ag ions in solution and thus allows the deposition of Ag nanoparticles directly on the surface. We investigate the influence of the layer stoichiometry and deposition parameters on the nucleation and growth of Ag nanoparticles, and show how they can be adjusted to control the nanoparticle size and density. We also demonstrate that this facile metallization process can be extended to PECVD SiOx layers, another dielectric coating of interest in photovoltaics. (C) 2011 Elsevier B.V. All rights reserved.