As (III) regularly requires oxidation to As (V), before it can be removed from water. Here, we reported photocatalytic removal of As (III) as well as adsorption of As (III) and As (V) using a novel, porous magnetic Ag/TiO2/Fe3O4@GO nanocomposite which was characterized via FT-IR, XRD, SEM, and TEM. A mathematical model (the central composite design) was used to estimate the relationship between the observed adsorption and our set of variables including initial concentration of arsenic ions, adsorbent dosage, pH, and the contact time. An optimum adsorption capacity of about 91% was observed for As (III) using 20 mg adsorbent with 24 ppm initial concentration of As (III), at pH = 5, within 90 min, and room temperature. Likewise, an optimum adsorption capacity of about 87% was observed for As (V) using 11 mg adsorbent with 17 ppm initial concentration of As (V), at pH = 3, within 30 min, and room temperature. The electrostatic factors between surface charge of nanocomposite and arsenic species were used to explain adsorption behavior of As (III) and As (V) at different conditions. The Langmuir isotherm equations best interpreted the nature of adsorption of As (III) and A (V). It was found during phocatalytic process maximum R% was about 63% for As (III) using 40 mg photocatalyst. Arsenic Adsorption Photocatalyst Magnetic nanocomposite Ag nanoparticles M. Miranzadeh et al.