The influence of the laser wavelength (308 and 1064 nm), number of shots, energy per pulse, background pressure and nitrogen atmosphere, on the phases formed during irradiation of low carbon steel samples, are reported. Each sample is morphologically and microstructurally characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM) and microprobe analysis. In order to characterise the corrosion behaviour, electrochemical tests in CO2 media such as potentio-dynamic curves and linear polarisation resistance are performed. The presence of different nitride phases is detected and investigated as a function of laser parameters and atmosphere. A better corrosion performance of the nitrided samples is observed, mainly after pre-corrosion. Nevertheless, more experimental work is needed to clarify the correlation between corrosion performance and treatment conditions. (C) 2002 Elsevier Science B.V. All rights reserved.