Unprecedented green marine nanosediment was utilized as an efficacious nanosorbent for removal of heptavalent manganese from aquatic matrices. The sediment samples were collected from Suez Gulf, Egypt, crushed into small particles and grinded into nanosized powder (40-60 nm). Characteristics of the produced nanosediment were confirmed via FT-IR, SEM and TEM. Thermal stability of the nanosediment was accomplished by the aid of TGA and TDA. The adsorption process of nanosediment for Mn(VII) using batch technique was optimized by different parameters including pH, stirring time, nanosorbent dose, Mn(VII) concentration, temperature and interfering ions. The optimum stirring time was 30 min, 0.02 g optimum dosage and the adsorption process was favored in acidic medium rather than alkaline one. The adsorption process fitted well with the linear Langmuir isotherm and pseudo-second order kinetics. The marine nanosediment was found promising for adsorption of Mn(VII) from high saline waters with recovery > 90%. (C) 2019 Elsevier B.V. All rights reserved.