One-step in situ preparation of silver nano-particles in polymethylmethacrylate (PMMA) using N,N'-dimethylformamide(DMF) as a medium has been performed successfully. The radical polymerization of methaycrylic acid (MMA), in presence of benzoyl peroxide followed by reaction of silver source has been successfully employed to synthesize Ag/PMMA nano-composite. A light yellow solution in its UV-Vis absorption spectrum showed surface plasmon resonance absorption bands between 410 and 425 nm in solutions and at about 452 nm in a transparent film. The Ag/PMMA nano-composite was characterized by X-ray diffraction (XRD) measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform-infrared spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA). XRD showed the fee crystal structure of the bulk Ag with particles of less than 25 nm in size similar to that is observed by TEM. SEM indicated uniform distribution of particles in the film. TGA confirmed enhanced thermal stability of the polymer. (c) 2007 Elsevier B.V. All rights reserved.