This paper examined the ability of iron-polyphenol complex nanoparticles (Fe-P NPs) synthesized by eucalyptus leaf extracts as a novel adsorptive flocculant to remove acid black 194 from aqueous solution. The influential parameters such as ratios of reagents, doses of Fe-P NPs, pH, temperatures and initial dye concentration were tested. The kinetics, experimental equilibrium and thermodynamic data for acid black 194 and Fe-P NPs systems were collected. The adsorption of dye on Fe-P NPs appears to be a physical process. This study confirms that removal of dye utilizing Fe-P NPs is more efficient than using traditional inorganic flocculant FeCl3. The Fe-P NPs could be employed as inexpensive and low-toxic adsorptive flocculant for removing dye from water Refereed/Peer-reviewed