In the present energy scenario of the world, hydrogen with high energy content seems to be a better green alternative to depleting fossil fuels. Here we describe an innovative and efficient iron nickel diselenide (Ni0.5Fe0.5Se2) as a potential electrocatalyst for hydrogen evolution reaction in acid media. Ni0.5Fe0.5Se2 has been fabricated by means of one-step hydrothermal process supported by multi walled carbon nanotubes (MWCNTs). Ni0.5Fe0.5Se2/MWCNTs electrocatalyst has been prepared from cost-effective and highly available earth-abundant elements. The crystalline structure, morphology and elemental composition of Ni0.5Fe0.5Se2/MWCNTs with different weight percentage (1, 3, 5, 7%) of MWCNTs in the composite. The electrocatalysts has been successfully evaluated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), field emission scanning electron microscopy (FE-SEM). Cyclic voltammetry (CV), Tafel and electrochemical impedance analysis have been utilized to investigate. Among the investigated weight percentages, the electrocatalyst with 3 wt% of MWCNT exhibited high hydrogen evolution activity with a current density of 10 mA/cm(2) at an overpotential 200 mV with a Tafel slope of 71 mVdec(-1). The synergistic efforts between Ni0.5Fe0.5Se2 and MWCNTs in the promotion of hydrogen evolution activity is ascribed to active sites, low electron transfer resistance and superior electrochemical kinetics of molecular hydrogen (H-2) production. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.