FexNi1-x nanostructures with different compositions (0 < x < 1.0) were electrodeposited from simple aqueous electrolytes with different ferric ion and nickel ion ratios. Composition, morphology, crystal structure, magnetic properties and electronegativity of the synthesized FexNi1-x nanostructures were systematically investigated. As the composition of Fe (x) in FexNi1-x nanostructures decreased from 1.0 to 0, the morphology changed from dendritic to nanoparticles and thin plates. The X-ray diffraction (XRD) patterns revealed that the dominant crystal structures shifted from metallic body centered cubic (bcc) for iron-rich FexNi1-x to mixed bcc and faced center cubic (fcc) for near equiatomic FeNi to rhombohedral/hexagonal for nickel-rich FeNi. The magnetic saturation and isoelectric point were also strongly dependent on nanostructure composition. Specifically, the magnetic saturation decreased and the isoelectric point increased with decreasing Fe content. When Fe content in FexNi1-x nanostructures was greater than 0.5 (x > 0.5), FexNi1-x nanostructures showed mainly metallic (zero-valent) Fe present as determined by XRD and selected area electron diffraction (SAED) patterns. Accordingly. Fe-1.0, Fe0.71Ni0.29 and Fe0.55Ni0.45 exhibited reactivity toward 1,1,1,2-tetrachloroethane, with Fe-1.0 yielding the greatest rate of reductive dechlorination. (C) 2009 Elsevier B.V. All rights reserved.