A novel aqueous dispersion of Fe(0) nanoparticles coated by inorganic sulphur-based structures. The product is extremly efficient in reduction of TCE while it keeps stable in water environment resulting in much better shelf life and longevity in comparision to standard products. The reactivity of NANOFER 25DS to chlorinated hydrocarbons is probably attributed to the higher hydrophobicity and conductivity of sulfide structures compared to iron oxides present on the surface of nanoparticles. The same structures inhibit corrosion of nanoparticles in water, improve resistance against fouling and passivation and result thus in higher longevity of nanoparticles.