Herein, a simple solvothermal co-reduction method was developed for the fabrication of three-dimensional (3D) uniform Pt66Ni34 nanoflowers (NFs) with highly rough surface and abundant active sites, where cetyltrimethylammonium chloride (CTAC) and citric acid were used as the structure-directing agent and reducing agent, respectively. The prepared Pt66Ni34 NFs exhibited enhanced catalytic properties towards hydrogen evolution reaction (HER) in both acidic and alkaline media. Specifically, the overpotential at 10 mA cm(-2) and Tafel slope of Pt66Ni34 NFs (43 mV, 33 mV dec(-1)) were similar to commercial Pt/C (20 wt%, 40 mV, 31 mV dec(-1)) in 0.5 M H2SO4. Moreover, Pt66Ni34 NFs displayed the smaller overpotential at 10 mA cm(-2) (50 mV) and Tafel slope (57 mV dec(-1)) as compared with Pt/C (63 mV, 69 mV dec(-1)) in 0.5 M KOH. And the catalyst exhibited superior durability for HER relative to Pt/C in both acidic and alkaline electrolytes. All these demonstrate the potential applications of Pt66Ni34 NFs in energy storage and conversion. (C) 2018 Elsevier Ltd. All rights reserved.