Intense electrical arcs were applied to thermoplastic (polyamide 66) and thermoset (fiber reinforced laminated polyester) materials and the resulting carbonization/metallization process was studied on a sub-micron scale with atomic force microscopy to understand very initial stage of reorganization of surface morphology. These changes can be critical in dramatic changes in surface resistivity preceding electric breakthrough. The surface microroughness and the localization of micro- and nanoparticles at the center (arc initiation area) and along the edges of the samples were significantly different for different arc regimes. We suggested that for thermoset, the material is pulled out of the surface in the arc formation area (the center of sample). Afterwards, the intensive re-deposition occurred along the edges enhancing nonuniform ablation around the arc initiation area. In contrary, for thermoplastic samples, the entire polymer surface was re-melted that resulted in dramatic smoothing of the initially non-uniform surface morphology. (c) 2005 Elsevier Ltd. All rights reserved.