Fe–Mn binary oxide was incorporated into diatomite (FMBO-diatomite) by a simple coating method. After being dried, the granular FMBO-diatomite was used as an absorbent in the removal of As(III). The strong oxidation and adsorption abilities of FMBO-diatomite were determined through batch equilibration experiments. Effects of temperature, pH, and coexisting anions on the As(III) adsorption efficiency were also studied