Recent studies suggest that the cupric oxide (CuO) nanoparticles effectively adsorb aqueous arsenic species under a wide range of water chemistries. However, to develop CuO nanotechnology to a field application level, further studies are necessary. Batch adsorption kinetic experiments were conducted to determine the time course of uptake of arsenic by CuO nanoparticles. A reactor with CuO nanoparticles was developed to conduct continuous flow-through experiments to filter arsenic from groundwater samples. Groundwater samples spiked with 100 mu g/L of arsenic were passed through (1 L/h) the flow-through reactor. Samples from the flow-through reactor were collected at a regular interval and analyzed for arsenic and other chemical components (e.g., pH, major and trace elements). The CuO nanoparticles adsorbed with arsenic were regenerated with a sodium hydroxide (NaOH) solution and tested again in the flow-through reactor. Three natural groundwater samples with above 10 mu g/L of arsenic were also tested with the flow-through reactor. The arsenic adsorption process by CuO nanoparticles was kinetically rapid and followed the pseudo-second-order rate. The continuous flow-through reactor with CuO nanoparticles was effective in filtering arsenic from spiked or natural groundwater. The regenerated CuO nanoparticles were also effective in filtering arsenic from groundwater. Arsenic mass balance data from regeneration studies suggested that 99% of input arsenic concentration was recovered. The CuO nanoparticle treatment did not show any discernible effects cm the chemical quality of groundwater samples. Results of this study suggest that CuO nanoparticles show potential for developing a simple process for field applications to remove arsenic from water. (C) 2013 Elsevier Inc. All rights reserved.