Crystalline maghemite (γ-Fe2O3) nanoparticles were cathodically electrodeposited at room temperature from environmentally benign electrolytes. The shape, size, and production rate of nanoparticles were strongly influenced by electrochemical conditions (e.g. FeCl3 concentration, current density). X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis indicated that randomly oriented polycrystalline maghemite nanoparticles were synthesized with the (3 1 1) and (4 4 0) peaks as the main diffraction peaks. Transmission electron microscopy (TEM) images revealed that average particle size decreased from approximately 23 to 7 nm with increased current density. Magnetic saturation (MS) of maghemite nanoparticles was determined to be 66 emu g-1 (66 Am2 kg-1) at 300 K. The present maghemite nanoparticles showed a greater As(V) adsorption compared to iron nanoparticles, which might be attributed to a higher specific surface area. © 2007 Elsevier B.V. All rights reserved.