The development of highly efficient and stable noble-metal-free electrocatalysts towards HER is of great significance. Herein, an electrodeposition method for the preparation of samarium oxide modified Ni-Co vertical nanosheets assembled three-dimensional honeycomb film on porous Ni foam (Sm2O3-Ni-Co/NF) is proposed. As-prepared Sm2O3-Ni-Co vertical nanosheets interweave together into a honeycomb morphology and uniformly cover the entire surface of Ni foam. The influence of content of Sm2O3 in electroplating bath on the electrocatalytic performances of Sm2O3-Ni-Co/NF electrode towards HER is studied in 1.0M KOH electrolyte. Polarization curve indicates that the self-supported Sm2O3-Ni-Co/NF electrode exhibits remarkably enhanced electrocatalytic activity towards HER. To attain a current density of 10mAcm(-2), Sm2O3-Ni-Co/NF electrode needs lower overpotential (276mV) than Ni-Co/NF electrode (301 mV). In addition, Sm2O3-Ni-Co/NF electrode exhibits a lower Tafel slope, demonstrating more favorable HER kinetics. Sm2O3-Ni-Co/NF electrode has smaller charge transfer resistance than Ni-Co/NF electrode, indicating a faster Faradic process and better HER kinetics. Besides, Sm2O3-Ni-Co/NF electrode features satisfactory long-term durability in alkaline media. The results indicate that Sm2O3-Ni-Co/NF electrode has potential application to water splitting devices for hydrogen generation. (C) 2019 Elsevier Ltd. All rights reserved.