How to improve the performance of ruthenium (Ru)-based catalysts for hydrogen evolution reaction (HER) to replace Pt is an interesting topic. Here, we in situ synthesize a polyaniline (PANI)-coated ultralow Ru-doped Ni(OH)(2) nanosheet (RuNi-NSs@PANI) in a 3D integral electrode via a facile dissolution-precipi tation strategy and electrodeposition. Results indicate that RuNi-NSs@PANI has a small overpotential of 21.9 mV at a current density of 10 mA cm(-2) and a low Tafel slope of 38.54 mV dec(-1) in alkaline condition, which is comparable with that of 20% Pt/C. The outstanding performance is attributed to the synergistic effects of the Ru-doped 2D Ni(OH)(2) structure, active metallic Ru cluster, PANI coating and 3D integrated Ni electrode. Owing to PANI coating, RuNi-NSs@PANI shows excellent durability with the increase of 36.8% current density retention (from 52.2% for RuNi-NSs increasing to 89% for RuNi-NSs@PANI) compared to the RuNi-NSs sample without PANI coating in strong acidic medium, because the PANI coating could keep H+. from cracking the catalyst structure and therefore enhance the stability. In short, this work indicates that RuNi-NSs@PANI composite is an excellent wide pH range HER catalyst. (C) 2019 Elsevier Inc. All rights reserved.