The synthesis of a novel hierarchical flower-like NiS via a solvothermal method for the electrochemcial oxidation of H 2 O 2 on a carbon paste electrode with high catalytic activity for the (MOR) in an alkaline medium has been reported. Novel nickel sulfide (NiS) hierarchical flower-like structures were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. A carbon paste electrode was modified with the as-prepared hierarchical flower-like NiS, resulting in a high electrocatalytic activity toward the oxidation of H 2 O 2 . The NiS-modified electrode was used for H 2 O 2 sensing, which was achieved over a wide linear range from 0.5 μM to 1.37 mM (I/μA = −0.19025 + 0.06094 C/mM) with a low limit of detection (LOD) of 0.3 μM and a limit of quantitation (LOQ) of 0.8 μM. The hierarchical flower-like NiS also exhibited a high electrocatalytic activity for the methanol oxidation reaction (MOR) in an alkaline medium with a high tolerance toward the catalyst-poisoning species generated during the MOR. The MOR proceeded via the direct electrooxidation of methanol on the oxidized NiS surface layer because the oxidation peak potential of the MOR was more positive than that of the oxidation of NiS. In recent years, a variety of metal sulfides nanostructures have been widely investigated due to their potential applications in energy storage and conversion devices, light-emitting diodes, photocatalytic and electrocatalytic reactions, sensors, thermoelectric devices, and memory devices. [21][22][23] In this work, we report the facile synthesis of NiS hierarchical flower-like nanostructures using a solvothermal route. The electrocatalytic performances of these NiS nanostructures were also investigated.Hydrogen peroxide (H 2 O 2 ) has attracted a great attention due to its importance as a reactive oxygen species and its involvement in chemical, biological, food-processing, medical, diagnostic, and environmental related fields. 35 have been employed for this purpose, the preparation of the hierarchical nanostructure with high surface area is still a challenge for fabricating an efficient sensing platform for H 2 O 2 .Pt-based materials are currently the most common electrocatalysts used as anodes in direct methanol fuel cells (DMFC) due to their high electrocatalytic activities. 36,37 However, Pt suffers from a high price and tendency to be poisoned by CO that occupies the active sites of the Pt via adsorption and block the transportation of z E-mail: baiqingyuan1981@126.com; c.fernandez@rgu.ac.uk methanol in its oxidation, limiting its utility in commercial applications. Therefore, the development of cost effective catalysts is highly desirable. Ni-based compounds are interesting alternatives to Pt due to their relative low costs and high electrocatalytic activity, which have attracted considerable recent attention 38,39 due to the Ni (II)/Ni (III) redox reactions. 40 To the best of our knowledge, this is the first time that the synthesis of a novel hierarchical flower-like NiS v...