Processes based on the use of iron-based nanoparticles (FeNPs) have proved to be a promising technology for the removal of a wide range of pollutants including metals and metalloids in water, being simple and low-cost procedures for removal of As(III)/As(V). FeNPs such as zerovalent iron nanoparticles (nZVI), nanoparticles of iron oxides (FeONPs) as hematite or magnetite, and iron-based nanoparticles prepared from natural extracts of plants or seeds (as yerba mate and green tea) have a larger surface area/volume ratio and exceptional adsorption properties compared with micro- or macrosized materials, with the advantages of an effective removal of pollutants at very low concentrations and a low generation of sludge. Laboratory experiments have been performed to evaluate the efficiency of some iron-based nanoparticles for removal of As(III)/(V), studying the influence of the initial concentration of the pollutant, the NP mass, the pollutant: FeNP molar ratio, pH, the presence of O2, among other variables. In this presentation, a brief review on the use of FeNPs for As removal from water and some results of our laboratory will be presented.