The micro-/nanoscopic structure of the hybrid organic-inorganic materials, based on polyether chains covalently linked to a silica framework through urea bridges, referred as ureasilicates or ureasils, and As2S3-ureasil composites with ion-implanted Ag nanoparticles is investigated. The formation of Ag nanoparticles is confirmed using optical transmission (surface plasmon resonance band of Ag nanoparticles) at ion-implantation doses of 2.5×1016 and 5.0×1016 ion/cm2 on the example of ureasil. It is established with scanning electron microscopy that incorporation of the As2S3 clusters into ureasil assists to ion-synthesis of Ag nanoparticles in polymer matrix, more effectively at higher doses of ion-implantation and for silver containing (As2S3)95Ag5-ureasil composite. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)