Increasing exposure to arsenic (As) contaminated ground water has become a global health hazard to humanity. Suitable adsorbent for As removal from water, especially for As(III) than As(V), is an urgent but still a challenging task. In this study, waste orange peel (OP) was modified with magnetic nanoparticles followed by calcination as a novel adsorbent and investigated for instantaneous oxidation and adsorption of As(III) from aqueous solutions. The batch adsorption experimental results showed that calcined magnetic orange peel composites (CMOPC) exhibited superior As(III) adsorption capacity (10.3 mg/g) as compared to similar cost effective adsorbents due to its high surface area, large pore size and greater numbers of active sites on its surface. The adsorption equilibrium data obeyed Langmuir model, and kinetic data was well described by the pseudo-second-order model. The adsorption mechanisms for As (III) might be involved ligand exchange of the hydroxyl in CMOPC to form Fe-O-As(III), and partial As (III) oxidation to As(V) followed by instantaneous adsorption on surface of CMOPC. The developed adsorbent has also demonstrated good anti-interference ability to co-existing ions, admirable regeneration ability and pronounced capacity in treating simulated real As(III) contaminated water. This study revealed that waste orange peel, after simple treatment could be used as a potential adsorbent for As (III) from aqueous solutions. (C) 2017 Elsevier Inc. All rights reserved.