Silver nanoparticles which are embedded in a polymer matrix exhibit an optical absorption in the visible and near-infrared region due to plasma resonance excitation The spectral position, the half width and the intensity of the plasma resonance absorption depend on the particle size, particle shape as well as on the optical behavior of the host material. The particle size and shape distribution was determined by transmission electron microscopy (TEM). Optical extinction and d.c. conductivity at one and the same silver particle assembly with large particles (D-m approximate to 50 nm) were measured simultaneously at 4.2 and 1.2 K as well as at room temperature. A significant blue shift of the plasma resonance absorption was found at low temperatures. The d.c. conductivity decreases up to two orders of magnitude and a significant photocurrent was measured.