Electric arc furnace dust from steelmaking were studied. The chemical analysis of the dusts was as follows (by weight): 27.0 % Fe; 7.1 % Mg; 4.9 % Zn; 4.0 % Ca and 0.5 % Pb. Spinels, Fe 3 O 4, CaCO 3 , SiO 2 , ZnO and PbO were the main mineral phases identified in the dusts through X-ray diffraction and Fourier transform infrared spectroscopy. Scanning electron microscopy showed that dusts comprised agglomerated spheroidal particles, whose sized ranged from 120 to 0.25 µm. The leachability of the dust was assessed during 28 days in percolation columns. Water and diluted organic acids were employed as leaching agents. The objective was to evaluate the behavior of this residue under conditions similar to those encountered in soils, as a consequence of microbial activity. The leachability of Zn and Pb was found to be between 80 and 16 mg per kg of dusts, per month.