Exfoliated colloidal MoS2 nano sheets with a size alternating from 5 to 10 nm have been successfully synthesized. The synthesis is accomplished through the formation of MoS2/TiO2 heterostructure containing single or weakly bounded 2-3 layer MoS2 sheets coated on 10 -15 nm TiO2 nanoparticles, followed by selective removal of TiO2 from the MoS2/TiO2 heterostructure. The synthesized sheets contain predominantly 1T phase (80%) with 2H phase. The electrochemical assessment demonstrates that colloidal MoS2 nano sheets exhibits outstanding performance in electrocatalytic hydrogen evolution reaction (HER) with a very low Tafel slope of 56 mV/dec, low onset overpotential, and excellent cycling stability in acidic media. This process also offers a one-pot method for the large scale production of 1T-MoS2 in its nano dimension. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.