An UV-enhanced single-step chemical bath process has been defined to produce precisely tailored colloidal solutions of silver nanoparticles capped with poly(methacrylic acid) (PMA) for biotechnological and packaging applications. The influence of the main process parameters on the nanoparticles chemical and structural characteristics, as well as on the reactions involved in the nanoparticle growth and polymer cross-linking, has been examined in details. A clear distinction between nanoparticle nucleation and growth, mediated by the available polymer functional groups and steric properties, has allowed to set up an effective controllable process and to obtain the desired colloids. The proper choice of the process parameters has led to a silver nanoparticles size smaller than 20 nm with a distribution peaked at less than 10 nm and stable over a period of one month. (C) 2009 Elsevier B.V. All rights reserved.