3D self-assembly polyethyleneimine-modified graphene oxide hydrogel (PEI-GH) was successfully synthesized via a simple one-step method without using other harsh chemicals. The unique three-dimensional (3D) porous network of PEI-GHs is achieved by using polyethyleneimine (PEI) as the cross-linking agent which also facilitate the self-assembly of GO sheets. With unique porous structure, large surface area and sufficient active sites, the PEI-GH has outstanding adsorption capacity (898mg/g), large removal rate (>90% at ppm level, or similar to 85% for ppb level simulated seawater) and high selectivity of uranium. The adsorption process was described well with the pseudo-second-order kinetic model and Langmuir isotherm model. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic. Based on the above results, the PEI-GH materials exhibits promising adsorption performance and high removal rate for uranium (VI) from aqueous solution and simulated seawater. (C) 2017 Elsevier B.V. All rights reserved.