The synthesis of selenium nanoparticles by pulsed laser ablation using a YAG laser at 532 nm is reported. The nanoparticles were deposited on three different substrates: metallic gold films, silicon wafers and glass, and subsequently visualized and characterized by atomic force microscopy (AFM). It was found that the size, shape and population of the selenium nanoparticles are strongly dependent on the experimental conditions during the ablation process; in particular on the energy density, number of laser pulses and the nature of the substrate. Atomic force microscopy imaging allows recognition, quantitative and qualitative characterization of individual selenium nanoparticles and their aggregates as well. In most of the experiments just a few laser pulses (up to five), were sufficient to produce a noticeable amount of nanoparticles on the substrate surface. (C) 2002 Published by Elsevier Science B.V.