This study focuses on the surface modification of a low alloy steel by XeCl laser under ambient conditions. These modifications were investigated employing two complementary methods. Auger electron spectroscopy. was employed for chemical characterisation and depth profile and scanning electron microscopy for the surface morphology after laser irradiation. It is shown that laser treatment induce the formation of Fe(III) oxide, mainly Fe2O3. This oxide can be described as a multilayer structure. One part, e.g. the upper layer, is formed with Fe2O3 aggregates due to the coalescence of small particles of Fe2O3 formed in the plasma by reaction of matter ejected from the surface with O-2 gas in the atmosphere. Under this layer deposited on the surface, we find a Fe2O3 structured layer corresponding to the oxidation of the melt layer. (C) 2003 Elsevier Science B.V. All rights reserved.