In this study, an iron oxyhydroxide nanocomposite with magnetic properties has been successfully synthesized. The quantification of the phases determined by Rietveld refinement has shown the presence of 74% of β-FeOOH (akaganeite) and 26% of Fe₃O₄ (magnetite). TEM images show aggregates of around 5-15 nm Fe₃O₄ nanoparticles with cubic morphology and β-FeOOH somatoids and nanorods with length and width of 100-200 nm and 10-50 nm, respectively. The estimated maximum adsorption capacities for As(III) and As(V) at pH 5 are similar (9 ± 1 and 8.1 ± 0.8 mg/g, respectively), suggesting the elimination of the oxidation step usually used in As(III) removal by precipitation. In low concentrations, the removal is efficient indicating that the magnetic composite shows potential for use in the removal of trace concentrations. Therefore, the magnetic nanocomposite shows potential for use in the removal of arsenic in aqueous media, eliminating the filtration step by applying a magnetic field.