Metallic polymorph of MoS 2 (1T-MoS 2 ) is an emerging and highly promising electrocatalyst owing to its high intrinsic conductivity, large interlayer spacing, hydrophilic surface, high specific surface area, faster in-plane charge transfer, and lower energy barrier for hydrogen adsorption and desorption. This article discusses a brief overview of electrocatalytic property evolutions of metallic 1T-MoS 2 for its application in electrocatalytic hydrogen production via water splitting. A summary is presented on various techniques that have been reported to date for developing the 1T-MoS 2 phase and their efficacy towards electrocatalytic hydrogen generation. This review also explains the thermodynamic parameter dependence of electrocatalytic enhancements of metallic MoS 2 with state-of-the-art theoretical reasoning and experimental details. The Gibbs free energy of adsorption/desorption of H 2 in 1T-MoS 2 is lower, and therefore outperforms electrocatalytic hydrogen production with respect to 2H–MoS 2 . The various engineering strategies, applied on the material, open avenues for systems devoted to water splitting. • Metallic polymorph (1T-MoS 2 ) of 2D-MoS 2 is an emerging and promising electrocatalyst for Hydrogen Evolution Reaction (HER). • 1T-MoS 2 exhibits lower Gibbs free energy of H 2 adsorption/desorption, thereby outperforms 2H–MoS 2 as electrocatalyst. • Various strategies are discussed for effective phase transition of 2D-MoS 2 from semiconducting (2H) to metallic (1T) MoS 2 . • Bandgap engineering, exposing active sites, and Fermi level alignment have shown extraordinary results for enhancing HER.